SwePub - sökning: WFRF:(Palermo Vincenzo)

Numrering	Referens	Omslagsbild	Hitta
1.	Anagnostopoulos, George, et al. (författare) Strain Engineering in Highly Wrinkled CVD Graphene/Epoxy Systems 2018 Ingår i: ACS Applied Materials & Interfaces. - : American Chemical Society (ACS). - 1944-8252 .- 1944-8244. ; 10:49, s. 43192-43202 Tidskriftsartikel (refereegranskat)abstract Chemical vapor deposition (CVD) is regarded as a promising fabrication method for the automated, large-scale, production of graphene and other two-dimensional materials. However, its full commercial exploitation is limited by the presence of structural imperfections such as folds, wrinkles, and even cracks that downgrade its physical and mechanical properties. For example, as shown here by means of Raman spectroscopy, the stress transfer from an epoxy matrix to CVD graphene is on average 30% of that of exfoliated monolayer graphene of over 10 μm in dimensions. However, in terms of electrical response, the situation is reversed; the resistance has been found here to decrease by the imposition of mechanical deformation possibly due to the opening up of the structure and the associated increase of electron mobility. This finding paves the way for employing CVD graphene/epoxy composites or coatings as conductive "networks" or bridges in cases for which the conductivity needs to be increased or at least retained when the system is under deformation. The tuning/control of such systems and their operative limitations are discussed here.
2.	Backes, Claudia, et al. (författare) 3-Dimensional graphene-like structures and applications: general discussion 2021 Ingår i: Faraday Discussions. - 1359-6640 .- 1364-5498. ; 227:0, s. 359-382 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
3.	Backes, Claudia, et al. (författare) Applications in opto-electronics: general discussion 2021 Ingår i: Faraday Discussions. - 1359-6640 .- 1364-5498. ; 227:0, s. 184-188 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
4.	Backes, Claudia, et al. (författare) Production and processing of graphene and related materials 2020 Ingår i: 2D Materials. - : IOP Publishing. - 2053-1583. ; 7:2 Tidskriftsartikel (refereegranskat)abstract We present an overview of the main techniques for production and processing of graphene and related materials (GRMs), as well as the key characterization procedures. We adopt a 'hands-on' approach, providing practical details and procedures as derived from literature as well as from the authors' experience, in order to enable the reader to reproduce the results. Section I is devoted to 'bottom up' approaches, whereby individual constituents are pieced together into more complex structures. We consider graphene nanoribbons (GNRs) produced either by solution processing or by on-surface synthesis in ultra high vacuum (UHV), as well carbon nanomembranes (CNM). Production of a variety of GNRs with tailored band gaps and edge shapes is now possible. CNMs can be tuned in terms of porosity, crystallinity and electronic behaviour. Section II covers 'top down' techniques. These rely on breaking down of a layered precursor, in the graphene case usually natural crystals like graphite or artificially synthesized materials, such as highly oriented pyrolythic graphite, monolayers or few layers (FL) flakes. The main focus of this section is on various exfoliation techniques in a liquid media, either intercalation or liquid phase exfoliation (LPE). The choice of precursor, exfoliation method, medium as well as the control of parameters such as time or temperature are crucial. A definite choice of parameters and conditions yields a particular material with specific properties that makes it more suitable for a targeted application. We cover protocols for the graphitic precursors to graphene oxide (GO). This is an important material for a range of applications in biomedicine, energy storage, nanocomposites, etc. Hummers' and modified Hummers' methods are used to make GO that subsequently can be reduced to obtain reduced graphene oxide (RGO) with a variety of strategies. GO flakes are also employed to prepare three-dimensional (3d) low density structures, such as sponges, foams, hydro- or aerogels. The assembly of flakes into 3d structures can provide improved mechanical properties. Aerogels with a highly open structure, with interconnected hierarchical pores, can enhance the accessibility to the whole surface area, as relevant for a number of applications, such as energy storage. The main recipes to yield graphite intercalation compounds (GICs) are also discussed. GICs are suitable precursors for covalent functionalization of graphene, but can also be used for the synthesis of uncharged graphene in solution. Degradation of the molecules intercalated in GICs can be triggered by high temperature treatment or microwave irradiation, creating a gas pressure surge in graphite and exfoliation. Electrochemical exfoliation by applying a voltage in an electrolyte to a graphite electrode can be tuned by varying precursors, electrolytes and potential. Graphite electrodes can be either negatively or positively intercalated to obtain GICs that are subsequently exfoliated. We also discuss the materials that can be amenable to exfoliation, by employing a theoretical data-mining approach. The exfoliation of LMs usually results in a heterogeneous dispersion of flakes with different lateral size and thickness. This is a critical bottleneck for applications, and hinders the full exploitation of GRMs produced by solution processing. The establishment of procedures to control the morphological properties of exfoliated GRMs, which also need to be industrially scalable, is one of the key needs. Section III deals with the processing of flakes. (Ultra)centrifugation techniques have thus far been the most investigated to sort GRMs following ultrasonication, shear mixing, ball milling, microfluidization, and wet-jet milling. It allows sorting by size and thickness. Inks formulated from GRM dispersions can be printed using a number of processes, from inkjet to screen printing. Each technique has specific rheological requirements, as well as geometrical constraints. The solvent choice is critical, not only for the GRM stability, but also in terms of optimizing printing on different substrates, such as glass, Si, plastic, paper, etc, all with different surface energies. Chemical modifications of such substrates is also a key step. Sections IV-VII are devoted to the growth of GRMs on various substrates and their processing after growth to place them on the surface of choice for specific applications. The substrate for graphene growth is a key determinant of the nature and quality of the resultant film. The lattice mismatch between graphene and substrate influences the resulting crystallinity. Growth on insulators, such as SiO2, typically results in films with small crystallites, whereas growth on the close-packed surfaces of metals yields highly crystalline films. Section IV outlines the growth of graphene on SiC substrates. This satisfies the requirements for electronic applications, with well-defined graphene-substrate interface, low trapped impurities and no need for transfer. It also allows graphene structures and devices to be measured directly on the growth substrate. The flatness of the substrate results in graphene with minimal strain and ripples on large areas, allowing spectroscopies and surface science to be performed. We also discuss the surface engineering by intercalation of the resulting graphene, its integration with Si-wafers and the production of nanostructures with the desired shape, with no need for patterning. Section V deals with chemical vapour deposition (CVD) onto various transition metals and on insulators. Growth on Ni results in graphitized polycrystalline films. While the thickness of these films can be optimized by controlling the deposition parameters, such as the type of hydrocarbon precursor and temperature, it is difficult to attain single layer graphene (SLG) across large areas, owing to the simultaneous nucleation/growth and solution/precipitation mechanisms. The differing characteristics of polycrystalline Ni films facilitate the growth of graphitic layers at different rates, resulting in regions with differing numbers of graphitic layers. High-quality films can be grown on Cu. Cu is available in a variety of shapes and forms, such as foils, bulks, foams, thin films on other materials and powders, making it attractive for industrial production of large area graphene films. The push to use CVD graphene in applications has also triggered a research line for the direct growth on insulators. The quality of the resulting films is lower than possible to date on metals, but enough, in terms of transmittance and resistivity, for many applications as described in section V. Transfer technologies are the focus of section VI. CVD synthesis of graphene on metals and bottom up molecular approaches require SLG to be transferred to the final target substrates. To have technological impact, the advances in production of high-quality large-area CVD graphene must be commensurate with those on transfer and placement on the final substrates. This is a prerequisite for most applications, such as touch panels, anticorrosion coatings, transparent electrodes and gas sensors etc. New strategies have improved the transferred graphene quality, making CVD graphene a feasible option for CMOS foundries. Methods based on complete etching of the metal substrate in suitable etchants, typically iron chloride, ammonium persulfate, or hydrogen chloride although reliable, are time- and resource-consuming, with damage to graphene and production of metal and etchant residues. Electrochemical delamination in a low-concentration aqueous solution is an alternative. In this case metallic substrates can be reused. Dry transfer is less detrimental for the SLG quality, enabling a deterministic transfer. There is a large range of layered materials (LMs) beyond graphite. Only few of them have been already exfoliated and fully characterized. Section VII deals with the growth of some of these materials. Amongst them, h-BN, transition metal tri- and di-chalcogenides are of paramount importance. The growth of h-BN is at present considered essential for the development of graphene in (opto) electronic applications, as h-BN is ideal as capping layer or substrate. The interesting optical and electronic properties of TMDs also require the development of scalable methods for their production. Large scale growth using chemical/physical vapour deposition or thermal assisted conversion has been thus far limited to a small set, such as h-BN or some TMDs. Heterostructures could also be directly grown. Section VIII discusses advances in GRM functionalization. A broad range of organic molecules can be anchored to the sp(2) basal plane by reductive functionalization. Negatively charged graphene can be prepared in liquid phase (e.g. via intercalation chemistry or electrochemically) and can react with electrophiles. This can be achieved both in dispersion or on substrate. The functional groups of GO can be further derivatized. Graphene can also be noncovalently functionalized, in particular with polycyclic aromatic hydrocarbons that assemble on the sp(2) carbon network by pi-pi stacking. In the liquid phase, this can enhance the colloidal stability of SLG/FLG. Approaches to achieve noncovalent on-substrate functionalization are also discussed, which can chemically dope graphene. Research efforts to derivatize CNMs are also summarized, as well as novel routes to selectively address defect sites. In dispersion, edges are the most dominant defects and can be covalently modified. This enhances colloidal stability without modifying the graphene basal plane. Basal plane point defects can also be modified, passivated and healed in ultra-high vacuum. The decoration of graphene with metal nanoparticles (NPs) has also received considerable attention, as it allows to exploit synergistic effects between NPs and graphene. Decoration can be either achieved chemically or in the gas phase. All LMs,
5.	Bellini, Daniele, et al. (författare) Allylic and Allenylic Dearomatization of Indoles promoted by Graphene Oxide via Covalent Grafting Activation Mode 2020 Ingår i: Chemistry - A European Journal. - : Wiley. - 1521-3765 .- 0947-6539. ; 26:46, s. 10427-10432 Tidskriftsartikel (refereegranskat)abstract The site‐selective allylative and allenylative dearomatization of indoles with alcohols is performed under carbocatalytic regime in the presence of graphene oxide (GO, 10 wt% loading) as the promoter. Metal‐free conditions, absence of stoichiometric additive, environmentally friendly conditions (H2O/CH3CN, 55 °C, 6 h), broad substrate scope (33 examples, yield up to 92%) and excellent site‐ and stereoselectivity characterize the present methodology. Moreover, a covalent activation model exerted by GO functionalities was corroborated by spectroscopic, experimental and computational evidences. Recovering and regeneration of the GO catalyst via simple acidic treatment was also documented.
6.	Boschi, Alex, et al. (författare) Mesoscopic 3D Charge Transport in Solution-Processed Graphene-Based Thin Films: A Multiscale Analysis 2023 Ingår i: Small. - 1613-6810 .- 1613-6829. ; 19:42 Tidskriftsartikel (refereegranskat)abstract Graphene and related 2D material (GRM) thin films consist of 3D assembly of billions of 2D nanosheets randomly distributed and interacting via van der Waals forces. Their complexity and the multiscale nature yield a wide variety of electrical characteristics ranging from doped semiconductor to glassy metals depending on the crystalline quality of the nanosheets, their specific structural organization ant the operating temperature. Here, the charge transport (CT) mechanisms are studied that are occurring in GRM thin films near the metal-insulator transition (MIT) highlighting the role of defect density and local arrangement of the nanosheets. Two prototypical nanosheet types are compared, i.e., 2D reduced graphene oxide and few-layer-thick electrochemically exfoliated graphene flakes, forming thin films with comparable composition, morphology and room temperature conductivity, but different defect density and crystallinity. By investigating their structure, morphology, and the dependence of their electrical conductivity on temperature, noise and magnetic-field, a general model is developed describing the multiscale nature of CT in GRM thin films in terms of hopping among mesoscopic bricks, i.e., grains. The results suggest a general approach to describe disordered van der Waals thin films.
7.	Dell'Elce, Simone, et al. (författare) 3D to 2D reorganization of silver-thiol nanostructures, triggered by solvent vapor annealing 2018 Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3372 .- 2040-3364. ; 10:48, s. 23018-23026 Tidskriftsartikel (refereegranskat)abstract Metal-organic composites are of great interest for a wide range of applications. The control of their structure remains a challenge, one of the problems being a complex interplay of covalent and supramolecular interactions. This paper describes the self-assembly, thermal stability and phase transitions of ordered structures of silver atoms and thiol molecules spanning from the molecular to the mesoscopic scale. Building blocks of molecularly defined clusters formed from 44 silver atoms, each particle coated by a monolayer of 30 thiol ligands, are used as ideal building blocks. By changing solvent and temperature it is possible to tune the self-assembled 3D crystals of pristine nanoparticles or, conversely, 2D layered structures, with alternated stacks of Ag atoms and thiol monolayers. The study investigates morphological, chemical and structural stability of these materials between 25 and 300 °C in situ and ex situ at the nanoscale by combining optical and electronic spectroscopic and scattering techniques, scanning probe microscopies and density-functional theory (DFT) calculations. The proposed wet-chemistry approach is relatively cheap, easy to implement, and scalable, allowing the fabricated materials with tuned properties using the same building blocks.
8.	Durso, M., et al. (författare) Biomimetic graphene for enhanced interaction with the external membrane of astrocytes 2018 Ingår i: Journal of Materials Chemistry B. - : Royal Society of Chemistry (RSC). - 2050-7518 .- 2050-750X. ; 6:33, s. 5335-5342 Tidskriftsartikel (refereegranskat)abstract Graphene and graphene substrates display huge potential as material interfaces for devices and biomedical tools targeting the modulation or recovery of brain functionality. However, to be considered reliable neural interfaces, graphene-derived substrates should properly interact with astrocytes, favoring their growth and avoiding adverse gliotic reactions. Indeed, astrocytes are the most abundant cells in the human brain and they have a crucial physiological role to maintain its homeostasis and modulate synaptic transmission. In this work, we describe a new strategy based on the chemical modification of graphene oxide (GO) with a synthetic phospholipid (PL) to improve interaction of GO with brain astroglial cells. The PL moieties were grafted on GO sheets through polymeric brushes obtained by atom-transfer radical-polymerization (ATRP) between acryloyl-modified PL and GO nanosheets modified with a bromide initiator. The adhesion of primary rat cortical astrocytes on GO-PL substrates increased by about three times with respect to that on glass substrates coated with standard adhesion agents (i.e. poly-d-lysine, PDL) as well as with respect to that on non-functionalized GO. Moreover, we show that astrocytes seeded on GO-PL did not display significant gliotic reactivity, indicating that the material interface did not cause a detrimental inflammatory reaction when interacting with astroglial cells. Our results indicate that the reported biomimetic approach could be applied to neural prosthesis to improve cell colonization and avoid glial scar formation in brain implants. Additionally, improved adhesion could be extremely relevant in devices targeting neural cell sensing/modulation of physiological activity.
9.	Ferrari, A. C., et al. (författare) Science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems 2015 Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3372 .- 2040-3364. ; 7:11, s. 4598-4810 Tidskriftsartikel (refereegranskat)abstract We present the science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems, targeting an evolution in technology, that might lead to impacts and benefits reaching into most areas of society. This roadmap was developed within the framework of the European Graphene Flagship and outlines the main targets and research areas as best understood at the start of this ambitious project. We provide an overview of the key aspects of graphene and related materials (GRMs), ranging from fundamental research challenges to a variety of applications in a large number of sectors, highlighting the steps necessary to take GRMs from a state of raw potential to a point where they might revolutionize multiple industries. We also define an extensive list of acronyms in an effort to standardize the nomenclature in this emerging field.
10.	Gazzano, Massimo, et al. (författare) A robust, modular approach to produce graphene-MO X multilayer foams as electrodes for Li-ion batteries 2019 Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3372 .- 2040-3364. ; 11:12, s. 5265-5273 Tidskriftsartikel (refereegranskat)abstract Major breakthroughs in batteries would require the development of new composite electrode materials, with a precisely controlled nanoscale architecture. However, composites used for energy storage are typically a disordered bulk mixture of different materials, or simple coatings of one material onto another. We demonstrate here a new technique to create complex hierarchical electrodes made of multilayers of vertically aligned nanowalls of hematite (Fe 2 O 3 ) alternated with horizontal spacers of reduced graphene oxide (RGO), all deposited on a 3D, conductive graphene foam. The RGO nanosheets act as porous spacers, current collectors and protection against delamination of the hematite. The multilayer composite, formed by up to 7 different layers, can be used with no further processing as an anode in Li-ion batteries, with a specific capacity of up to 1175 μA h cm -2 and a capacity retention of 84% after 1000 cycles. Our coating strategy gives improved cyclability and rate capacity compared to conventional bulk materials. Our production method is ideally suited to assemble an arbitrary number of organic-inorganic materials in an arbitrary number of layers.
11.	Gazzi, Arianna, et al. (författare) Graphene, other carbon nanomaterials and the immune system: toward nanoimmunity-by-design 2020 Ingår i: JPhys Materials. - : IOP Publishing. - 2515-7639. ; 3:3 Tidskriftsartikel (refereegranskat)abstract Carbon-based materials (CBMs), such as graphene, nanodiamonds, carbon fibers, and carbon dots, have attracted a great deal scientific attention due to their potential as biomedical tools. Following exposure, particularly intravenous injection, these nanomaterials can be recognized by immune cells. Such interactions could be modulated by the different physicochemical properties of the materials (e.g. structure, size, and chemical functions), by either stimulating or suppressing the immune response. However, a harmonized cutting-edge approach for the classification of these materials based not only on their physicochemical parameters but also their immune properties has been missing. The European Commission-funded G-IMMUNOMICS and CARBO-IMmap projects aimed to fill this gap, developing a functional pipeline for the qualitative and quantitative immune characterization of graphene, graphene-related materials (GRMs), and other CBMs. The goal was to open breakthrough perspectives for the definition of the immune profiles of these materials. Here, we summarize our methodological approach, key results, and the necessary multidisciplinary expertise ranging across various fields, from material chemistry to engineering, immunology, toxicology, and systems biology. G-IMMUNOMICS, as a partnering project of the Graphene Flagship, the largest scientific research initiative on graphene worldwide, also complemented the studies performed in the Flagship on health and environmental impact of GRMs. Finally, we present the nanoimmunity-by-design concept, developed within the projects, which can be readily applied to other 2D materials. Overall, the G-IMMUNOMICS and CARBO-IMmap projects have provided new insights on the immune impact of GRMs and CBMs, thus laying the foundation for their safe use and future translation in medicine.
12.	Greijer, Helena, et al. (författare) Tuneable conductivity at extreme electric fields in ZnO tetrapod-silicone composites for high-voltage power cable insulation 2022 Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 12:1, s. 6035- Tidskriftsartikel (refereegranskat)abstract Resistive Field Grading Materials (RFGM) are used in critical regions in the electrical insulation system of high-voltage direct-current cable systems. Here, we describe a novel type of RFGM, based on a percolated network of zinc oxide (ZnO) tetrapods in a rubber matrix. The electrical conductivity of the composite increases by a factor of 108 for electric fields > 1 kV mm-1, as a result of the highly anisotropic shape of the tetrapods and their significant bandgap (3.37 eV). We demonstrate that charge transport at fields < 1 kV mm-1 is dominated by thermally activated hopping of charge carriers across spatially, as well as energetically, localized states at the ZnO-polymer interface. At higher electric fields (> 1 kV mm-1) band transport in the semiconductive tetrapods triggers a large increase in conductivity. These geometrically enhanced ZnO semiconductors outperform standard additives such as SiC particles and ZnO micro varistors, providing a new class of additives to achieve variable conductivity in high-voltage cable system applications.
13.	Khaliha, Sara, et al. (författare) Defective graphene nanosheets for drinking water purification : Adsorption mechanism, performance, and recovery 2021 Ingår i: FlatChem. - : Elsevier. - 2452-2627. ; 29 Tidskriftsartikel (refereegranskat)abstract Defect-rich graphene oxide (dGO) was used as sorbent for organic contaminants of emerging concern in tap water, including drugs and dyes, and the performance compared to those of lower-defects graphene types. The role of holes and carbonyl- carboxylic groups on graphene nanosheets surface on the adsorption mechanism and efficiency was investigated. dGO showed enhanced adsorption capacity toward two fluoroquinolone antibiotics (ofloxacin, OFLOX, and ciprofloxacin, CIPRO) in tap water with a maximum capacity of 650 mg/g, compared to 204 mg/g for Hummers derived commercial GO (hGO) and 125 mg/g for less defected Brodie derived GO (bGO) for OFLOX. The role of defects on the selective adsorption of OFLOX was also modelled by MD simulations, highlighting a mechanism mainly driven by the shape complementarity between the graphene holes and the molecules. Adsorption isotherms revealed different adsorption model for dGO, with a Langmuir fitting for dGO and BET fitting for all the other investigated samples. The maximum adsorption capacity of dGO for OFLOX was about six times higher than that of Granular Activated Carbon (95 mg/g), the industrial adsorption standard technology. Finally, it was also demonstrated that dGO can be recovered from treated water by ultrafiltration, this preventing secondary contamination risks and enabling safe use of graphene nanosheets for water purification.
14.	Khaliha, Sara, et al. (författare) Upcycling of plastic membrane industrial scraps and reuse as sorbent for emerging contaminants in water 2024 Ingår i: Environmental Science: Water Research and Technology. - 2053-1419 .- 2053-1400. ; 10:5, s. 1097-1107 Tidskriftsartikel (refereegranskat)abstract Scraps obtained as waste of the industrial production of polysulfone and polysulfone-graphene oxide hollow fiber membranes (PSU-HF and PSU-GO-HF, respectively) were converted into granular materials and used as sorbents of several classes of emerging and standard water contaminants, such as drugs, heavy metal ions, and a mixture of per- and poly-fluoroalkyl substances (PFASs). The millimetric sized granules (PSU and PSU-GO, respectively) outperformed granular activated carbon (GAC), the industrial sorbent benchmark, in the adsorption of lead, diclofenac, and PFOA from tap water. Adsorption mechanism insight was achieved by molecular dynamics simulations, demonstrating the key role of graphene oxide (GO) on PSU-GO material performance. With respect to GAC, PSU-GO adsorption capacity was two times higher for diclofenac and PFOA and ten times higher for lead. Material safety was assessed by surface enhanced Raman spectroscopy, excluding GO nanosheets leaching, and combined potability test. Overall, our work proves that scrap conversion and reuse is a valuable strategy to reduce plastic industrial waste disposal and to integrate standard technology for enhanced water purification.
15.	Kovtun, Alessandro, et al. (författare) Accurate chemical analysis of graphene-based materials using X-ray photoelectron spectroscopy 2019 Ingår i: Carbon. - : Elsevier BV. - 0008-6223. ; 143, s. 268-275 Tidskriftsartikel (refereegranskat)abstract A simple, fast and general protocol for quantitative analysis of X-ray photoelectron spectroscopy (XPS) data provides accurate estimations of chemical species in graphene and related materials (GRMs). XPS data are commonly used to estimate the quality of and defects in graphene and graphene oxide (GO), by comparing carbon and oxygen 1s XPS peaks, obtaining an O/C ratio. This approach, however, cannot be used in the presence of extraneous oxygen contamination. The protocol, based on quantitative line-shape analysis of C 1s signals, uses asymmetric pseudo- Voigt line-shapes (APV), in contrast to Gaussian-based approaches conventionally used in fitting XPS spectra, thus allowing better accuracy in quantifying C 1s contributions from graphitic carbon (sp2), defects (sp3 carbon), carbons bonded to hydroxyl and epoxy groups, and from carbonyl and carboxyl groups. The APV protocol was evaluated on GRMs with O/C ratios ranging from 0.02 to 0.30 with film thicknesses from monolayers to bulk-like (>30nm) layers and also applied to previously published data, showing better results compared to those from conventional XPS fitting protocols. Based uniquely on C 1s data, the APV protocol can quantify O/C ratio and the presence of specific functional groups in GRMs even on SiOx, substrates, or in samples containing water.
16.	Kovtun, Alessandro, et al. (författare) Benchmarking of graphene-based materials: Real commercial products versus ideal graphene 2019 Ingår i: 2D Materials. - : IOP Publishing. - 2053-1583. ; 6:2 Tidskriftsartikel (refereegranskat)abstract There are tens of industrial producers claiming to sell graphene and related materials (GRM), mostly as solid powders. Recently the quality of commercial GRM has been questioned, and procedures for GRM quality control were suggested using Raman Spectroscopy or Atomic Force Microscopy. Such techniques require dissolving the sample in solvents, possibly introducing artefacts. A more pragmatic approach is needed, based on fast measurements and not requiring any assumption on GRM solubility. To this aim, we report here an overview of the properties of commercial GRM produced by selected companies in Europe, USA and Asia. We benchmark: (A) size, (B) exfoliation grade and (C) oxidation grade of each GRM versus the ones of 'ideal' graphene and, most importantly, versus what reported by the producer. In contrast to previous works, we report explicitly the names of the GRM producers and we do not re-dissolve the GRM in solvents, but only use techniques compatible with industrial powder metrology. A general common trend is observed: Products having low defectivity (%sp 2 bonds >95%) feature low surface area (<200 m 2 g -1 ), while highly exfoliated GRM show a lower sp 2 content, demonstrating that it is still challenging to exfoliate GRM at industrial level without adding defects.
17.	Kovtun, Alessandro, et al. (författare) Core-shell graphene oxide-polymer hollow fibers as water filters with enhanced performance and selectivity 2021 Ingår i: Faraday Discussions. - : Royal Society of Chemistry (RSC). - 1359-6640 .- 1364-5498. ; 227, s. 274-290 Tidskriftsartikel (refereegranskat)abstract Commercial hollow fiber filters for micro- and ultrafiltration are based on size exclusion and do not allow the removal of small molecules such as antibiotics. Here, we demonstrate that a graphene oxide (GO) layer can be firmly immobilized either inside or outside polyethersulfone-polyvinylpyrrolidone hollow fiber (Versatile PES (R), hereafter PES) modules and that the resulting core-shell fibers inherits the microfiltration ability of the pristine PES fibers and the adsorption selectivity of GO. GO nanosheets were deposited on the fiber surface by filtration of a GO suspension through a PES cartridge (cut-off 0.1-0.2 mu m), then fixed by thermal annealing at 80 degrees C, rendering the GO coating stably fixed and unsoluble. The filtration cut-off, retention selectivity and efficiency of the resulting inner and outer modified hollow fibers (HF-GO) were tested by performing filtration on water and bovine plasma spiked with bovine serum albumin (BSA, 66 kDa, approximate to 15 nm size), monodisperse polystyrene nanoparticles (52 nm and 303 nm sizes), with two quinolonic antibiotics (ciprofloxacin and ofloxacin) and rhodamine B (RhB). These tests showed that the microfiltration capability of PES was retained by HF-GO, and in addition the GO coating can capture the molecular contaminants while letting through BSA and smaller polystyrene nanoparticles. Combined XRD, molecular modelling and adsorption experiments show that the separation mechanism does not rely only on physical size exclusion, but involves intercalation of solute molecules between the GO layers.
18.	Kovtun, Alessandro, et al. (författare) Graphene oxide–polysulfone filters for tap water purification, obtained by fast microwave oven treatment 2019 Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3372 .- 2040-3364. ; 11:11, s. 22780-22787 Tidskriftsartikel (refereegranskat)abstract The availability of clean, pure water is a major challenge for the future of our society. 2-Dimensional nanosheets of GO seem promising as nanoporous adsorbent or filters for water purification; however, their processing in macroscopic filters is challenging, and their cost vs. standard polymer filters is too high. Here, we describe a novel approach to combine graphene oxide (GO) sheets with commercial polysulfone (PSU) membranes for improved removal of organic contaminants from water. The adsorption physics of contaminants on the PSU-GO composite follows Langmuir and Brunauer–Emmett–Teller (BET) models, with partial swelling and intercalation of molecules in between the GO layers. Such a mechanism, well-known in layered clays, has not been reported previously for graphene or GO. Our approach requires minimal amounts of GO, deposited directly on the surface of the polymer, followed by stabilization using microwaves or heat. The purification efficiency of the PSU-GO composites is significantly improved vs. benchmark commercial PSU, as demonstrated by the removal of two model contaminants, rhodamine B and ofloxacin. The excellent stability of the composite is confirmed by extensive (100 hours) filtration tests in commercial water cartridges.
19.	Kovtun, Alessandro, et al. (författare) Multifunctional graphene oxide/biopolymer composite aerogels for microcontaminants removal from drinking water 2020 Ingår i: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 259:November 2020 Tidskriftsartikel (refereegranskat)abstract Due to water depletion and increasing level of pollution from standard and emerging contaminants, the development of more efficient purification materials and technology for drinking water treatment is a crucial challenge to be addressed in the near future. Graphene oxide (GO) has been pointed as one of the most promising materials to build structure and devices for new adsorbents and filtration systems. Here, we analyzed two types of GO doped 3D chitosan-gelatin aerogels with GO sheets embedded in the bulk or deposited on the surface. Through combined structural characterization and adsorption tests on selected proxies of drinking water micropollutants, we compared both GO-embedded and GO-coated materials and established the best architecture for achieving enhanced removal efficiency toward con- taminants in water. To evaluate the best configuration, we studied the adsorption capacity of both systems on two organic molecules (i.e., fluoroquinolonic antibiotics ofloxacin and ciprofloxacin) and a heavy metal (lead Pb2þ) of great environmental relevance and with already proved high affinity for GO. The Pb monolayer maximum adsorption capacity qmax was 11.1 mg/g for embedded GO aerogels and 1.5 mg/g in coated GO-ones. Only minor differences were found for organic contaminants between coating and embedding approaches with an adsorption capacity of 5e8 mg/g and no adsorption was found for chitosan-gelatin control aerogels without GO. Finally, potential antimicrobial effects were found particularly for the GO-coated aerogels materials, thus corroborating the multifunctionality of the newly developed porous structures.
20.	Kovtun, Alessandro, et al. (författare) Multiscale Charge Transport in van der Waals Thin Films: Reduced Graphene Oxide as a Case Study 2021 Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-086X .- 1936-0851. ; 15:2, s. 2654-2667 Tidskriftsartikel (refereegranskat)abstract Large area van der Waals (vdW) thin films are assembled materials consisting of a network of randomly stacked nanosheets. The multiscale structure and the two-dimensional (2D) nature of the building block mean that interfaces naturally play a crucial role in the charge transport of such thin films. While single or few stacked nanosheets (i.e., vdW heterostructures) have been the subject of intensive works, little is known about how charges travel through multilayered, more disordered networks. Here, we report a comprehensive study of a prototypical system given by networks of randomly stacked reduced graphene oxide 2D nanosheets, whose chemical and geometrical properties can be controlled independently, permitting to explore percolated networks ranging from a single nanosheet to some billions with room-temperature resistivity spanning from 10-5 to 10-1 ω·m. We systematically observe a clear transition between two different regimes at a critical temperature T*: Efros-Shklovskii variable-range hopping (ES-VRH) below T∗ and power law behavior above. First, we demonstrate that the two regimes are strongly correlated with each other, both depending on the charge localization length ζ, calculated by the ES-VRH model, which corresponds to the characteristic size of overlapping sp2 domains belonging to different nanosheets. Thus, we propose a microscopic model describing the charge transport as a geometrical phase transition, given by the metal-insulator transition associated with the percolation of quasi-one-dimensional nanofillers with length ζ, showing that the charge transport behavior of the networks is valid for all geometries and defects of the nanosheets, ultimately suggesting a generalized description on vdW and disordered thin films.
21.	Kurapati, Rajendra, et al. (författare) Biodegradation of graphene materials catalyzed by human eosinophil peroxidase 2021 Ingår i: Faraday Discussions. - : Royal Society of Chemistry (RSC). - 1359-6640 .- 1364-5498. ; 227:0, s. 189-203 Tidskriftsartikel (refereegranskat)abstract Understanding the biodegradability of graphene materials by the action of oxidative enzymes secreted by immune cells is essential for developing applicable biomedical products based on these materials. Herein, we demonstrate the biodegradation of graphene oxide (GO) by recombinant eosinophil peroxidase (EPO) enzyme extracted from human eosinophils in the presence of a low concentration of hydrogen peroxide and NaBr. We compared the degradation capability of the enzyme on three different GO samples containing different degrees of oxygen functional groups on their graphenic lattices. EPO succeeded in degrading the three tested GO samples within 90 h treatment. Raman spectroscopy and transmission electron microscopy analyses provided clear-cut evidence for the biodegradation of GO by EPO catalysis. Our results provide more insight into a better understanding of the biodegradation of graphene materials, helping the design of future biomedical products based on these carbon nanomaterials.
22.	Lancellotti, Lidia, et al. (författare) Selective ion transport in large-area graphene oxide membrane filters driven by the ionic radius and electrostatic interactions 2024 Ingår i: Nanoscale. - 2040-3372 .- 2040-3364. ; 16:14, s. 7123-7133 Tidskriftsartikel (refereegranskat)abstract Filters made of graphene oxide (GO) are promising for purification of water and selective sieving of specific ions; while some results indicate the ionic radius as the discriminating factor in the sieving efficiency, the exact mechanism of sieving is still under debate. Furthermore, most of the reported GO filters are planar coatings with a simple geometry and an area much smaller than commercial water filters. Here, we show selective transport of different ions across GO coatings deposited on standard hollow fiber filters with an area >10 times larger than typical filters reported. Thanks to the fabrication procedure, we obtained a uniform coating on such complex geometry with no cracks or holes. Monovalent ions like Na+ and K+ can be transported through these filters by applying a low electric voltage, while divalent ions are blocked. By combining transport and adsorption measurements with molecular dynamics simulations and spectroscopic characterization, we unravel the ion sieving mechanism and demonstrate that it is mainly due to the interactions of the ions with the carboxylate groups present on the GO surface at neutral pH.
23.	Liscio, Andrea, et al. (författare) Local Surface Potential of pi-Conjugated Nanostructures by Kelvin Probe Force Microscopy: Effect of the Sampling Depth 2011 Ingår i: SMALL. - : John Wiley and Sons, Ltd. - 1613-6810. ; 7:5, s. 634-639 Tidskriftsartikel (refereegranskat)abstract Kelvin probe force microscopy (KPFM) is usually applied to map the local surface potential of nanostructured materials at surfaces and interfaces. KPFM is commonly defined as a surface technique, even if this assumption is not fully justified. However, a quantification of the surface sensitivity of this technique is crucial to explore electrical properties at the nanoscale. Here a versatile 3D model is presented which provides a quantitative explanation of KPFM results, taking into account the vertical structure of the sample. The model is tested on nanostructured films obtained from two relevant semiconducting systems for field-effect transistor and solar cell applications showing different interfacial properties, i.e., poly(3-hexylthiophene) (P3HT) and perylene-bis-dicarboximide (PDI). These findings are especially important since they enable quantitative determination of the local surface potential of conjugated nanostructures, and thereby pave the way towards optimization of the electronic properties of nanoscale architectures for organic electronic applications.
24.	Maccaferri, Giulio, et al. (författare) Highly sensitive amperometric sensor for morphine detection based on electrochemically exfoliated graphene oxide. Application in screening tests of urine samples 2019 Ingår i: Sensors and Actuators, B: Chemical. - : Elsevier BV. - 0925-4005. ; 281, s. 739-745 Tidskriftsartikel (refereegranskat)abstract Graphene oxide modified screen-printed electrodes have been tested as amperometric sensors for morphine determination. The results demonstrate that the arising of electrocatalytic processes ascribable to the graphene coating, combined with the use of a suitable cleaning procedure, allow the sensor to achieve higher sensitivity (2.61 nA ppb−1) and lower limit of detection (2.5 ppb) with respect to those reported in the literature for similar devices. Due to very low detection limit found, the device is suitable to detect the presence of morphine in urine samples after a very simple and rapid pre-treatment of the matrix, allowing the removal of interfering species affecting the voltammetric responses. Tests performed in synthetic urine samples demonstrate that the presence of the electrocatalytic coating is mandatory in resolving the peak due to morphine oxidation in respect to uric acid. The sensor proposed is, thus, suitable to detect this drug even at concentration values below the cut-off levels defined by European and American regulations. These results allow us to propose the sensor for screening tests in portable devices, to be applied in systematic controls of drug abuses, e.g. in drivers and in men at work
25.	Mantovani, Sebastiano, et al. (författare) Amino acid-driven adsorption of emerging contaminants in water by modified graphene oxide nanosheets 2023 Ingår i: Environmental Science: Water Research and Technology. - : Royal Society of Chemistry (RSC). - 2053-1419 .- 2053-1400. ; 9:4, s. 1030-1040 Tidskriftsartikel (refereegranskat)abstract Graphene oxide nanosheets have shown promising adsorption properties toward emerging organic contaminants in drinking water. Here, we report a family of graphene oxide nanosheets covalently modified with amino acids and the study on their adsorption properties toward a mixture of selected contaminants, including pharmaceuticals, additives, and dyes. Graphene oxides modified with l-glutamic acid and l-methionine (GO-Glu and GO-Met) were synthesized and purified with a scalable and fast synthetic and purification procedure, and their structure was studied by combined X-ray photoelectron spectroscopy and elemental analysis. An amino acid loading of about 5% and a slight reduction (from 27% down to 14-20% oxygen) were found and associated with the adsorption selectivity. They were compared to unmodified GO, reduced GO (rGO), GO-lysine, and to the reference sample GO-NaOH. Each type of modified GO possesses a higher adsorption capacity toward bisphenol A (BPA), benzophenone-4 (BP4), and carbamazepine (CBZ) than standard GO and rGO, and the adsorption occurred within the first hour of contact time. The maximum adsorption capacity (estimated from the adsorption isotherms) was strictly related to the amino acid loading. Accordingly, molecular dynamics simulations highlighted higher interaction energies for the modified GOs than unmodified GO, as a result of higher van der Waals and hydrophobic interactions between the contaminants and the amino acid side chains on the nanosheet surface.
26.	Marsden, A. J., et al. (författare) Electrical percolation in graphene-polymer composites 2018 Ingår i: 2D Materials. - : IOP Publishing. - 2053-1583. ; 5:3 Forskningsöversikt (refereegranskat)abstract Electrically conductive composites comprising polymers and graphene are extremely versatile and have a wide range of potential applications. The conductivity of these composites depends on the choice of polymer matrix, the type of graphene filler, the processing methodology, and any post-production treatments. In this review, we discuss the progress in graphene-polymer composites for electrical applications. Graphene filler types are reviewed, the progress in modelling these composites is outlined, the current optimal composites are presented, and the example of strain sensors is used to demonstrate their application.
27.	Moro, Giulia, et al. (författare) Amino acid modified graphene oxide for the simultaneous capture and electrochemical detection of glyphosate 2024 Ingår i: Materials Today Chemistry. - 2468-5194. ; 36 Tidskriftsartikel (refereegranskat)abstract Amino acid modified graphene oxide derivatives (GO-AA) are herein proposed as active materials for the capture and consequent electrochemical detection of organic pollutants in aqueous media. Glyphosate (GLY), an herbicide present in many water compartments, was chosen as benchmark species to test the effectiveness of these materials for its electroactive nature, allowing direct evidence of the capture event. L-Lysine, L-Arginine or L-Methionine were grafted on GO surface through epoxide ring opening reaction, promoting the amino acids binding and the concomitant partial reduction of GO. The synthetic process results in a charge resistance drop from 8.1 KΩ for GO to 0.8–2.1 KΩ for the various GO-AA, supporting the applicability of these materials in electrochemical sensing. The resulting GO-Lysine, GO-Arginine and GO-Methionine were exploited for GLY adsorption from water. GO-Lysine was found to have the strongest interaction with GLY, with a removal efficiency of 76 % after 1 h, which is about two-fold higher than those of granular activated carbon, the industrial benchmark adsorbent. GO-AAs outperform the pristine unmodified material also when exploited as active materials for the capturing and following electrochemical detection of GLY. GO-Lysine showed the best sensitivity and allowed the recognition of GLY in water even when present at concentration levels down to 2 μg/L. Molecular dynamics simulations confirmed that the enhanced performance of this material can be ascribed to the hydrogen bond and salt bridge interactions between Lys moieties and GLY, originated from hydrogen bond and salt bridge interactions.
28.	Pathipati, Srinivasa Rao, et al. (författare) The role of charge transfer at reduced graphene oxide/organic semiconductor interface on the charge transport properties 2020 Ingår i: Organic Electronics: physics, materials, applications. - : Elsevier BV. - 1566-1199. ; 77 Tidskriftsartikel (refereegranskat)abstract The effect of 1-pyrenesulfonicacid sodium salt (1-PSA), tetracyanoethylene (TCNE) and tetrafluoro-tetracyanoquinodimethane (F4-TCNQ) on charge transport properties of reduced graphene oxide (RGO) is examined by measuring the transfer characteristics of field-effect transistors and co-planar time-of-flight photocurrent technique. Evidence of p-type doping and a reduction of mobility of electrons in RGO upon deposition of these materials is observed. Time-resolved photocurrent measurements show a reduction in electron mobility even at submonolayer coverage of these materials. The variation of transit time with different coverages reveals that electron mobility decreases with increasing the surface coverage of 1-PSA, TCNE and F4-TCNQ to a certain extent, while at higher coverage the electron mobility is slightly recovered. All three molecules show the same trend in charge carrier mobility variation with coverage, but with different magnitude. Among all three molecules, 1-PSA acts as weak electron acceptor compared to TCNE and F4-TCNQ. The additional fluorine moieties in F4-TCNQ provides excellent electron withdrawing capability compared to TCNE. The experimental results are consistent with the density functional theory calculations.
29.	Pierleoni, Davide, et al. (författare) Selective Gas Permeation in Graphene Oxide-Polymer Self-Assembled Multilayers 2018 Ingår i: ACS Applied Materials & Interfaces. - : American Chemical Society (ACS). - 1944-8252 .- 1944-8244. ; 10:13, s. 11242-11250 Tidskriftsartikel (refereegranskat)abstract The performance of polymer-based membranes for gas separation is currently limited by the Robeson limit, stating that it is impossible to have high gas permeability and high gas selectivity at the same time. We describe the production of membranes based on the ability of graphene oxide (GO) and poly(ethyleneimine) (PEI) multilayers to overcome such a limit. The PEI chains act as molecular spacers in between the GO sheets, yielding a highly reproducible, periodic multilayered structure with a constant spacing of 3.7 nm, giving a record combination of gas permeability and selectivity. The membranes feature a remarkable gas selectivity (up to 500 for He/CO 2 ), allowing to overcome the Robeson limit. The permeability of these membranes to different gases depends exponentially on the diameter of the gas molecule, with a sieving mechanism never obtained in pure GO membranes, in which a size cutoff and a complex dependence on the chemical nature of the permeant is typically observed. The tunable permeability, the high selectivity, and the possibility to produce coatings on a wide range of polymers represent a new approach to produce gas separation membranes for large-scale applications.
30.	Pierleoni, Davide, et al. (författare) Structure and sieving mechanism of high selective graphene-based membranes 2018 Ingår i: AIP Conference Proceedings. - : Author(s). - 1551-7616 .- 0094-243X. ; 1981 Konferensbidrag (refereegranskat)abstract Graphene oxide was used as charge able to confer high selectivity to the final product. A self-assembling technique, namely layer-by-layer has been developed to stratify graphene-based coating on polymeric films; this coating is composed by nanolayers of graphene oxide alternated with polymers, bonded each other by electrostatic forces. Permeability measurement on layered Matrimid®, a commercial polyimide, showed incredibly high selectivity values to small particle mixtures, as O2, CO2, He and H2. Through simple post-treatments the selective performance was also improved, as demonstration of potentiality of the well-ordered bi-dimensional system: improvement on the coating would make this material one of the viable solution for industrial separations, e.g. hydrogen purification in sustainable energy production. A further investigation on similar structures obtained by other strategies shall demonstrate the peculiar mechanism occurring in this material for high selective performance.
31.	Poletti, Fabrizio, et al. (författare) Continuous capillary-flow sensing of glucose and lactate in sweat with an electrochemical sensor based on functionalized graphene oxide 2021 Ingår i: Sensors and Actuators, B: Chemical. - : Elsevier BV. - 0925-4005. ; 344 Tidskriftsartikel (refereegranskat)abstract We describe an electrochemical device for the simultaneous monitoring of glucose and lactate in sweat, based on enzymatic sensors exploiting capillary flow to induce continuous, stable sensing. The enzymes, namely glucose oxidase and lactate oxidase, were anchored to a graphene oxide and chitosan composite (GO-Ch) of original synthesis, to achieve stable deposition of the bioreceptors on the electrochemical platform. We tested both biosensors on a realistic device architecture: they were embedded in a nitrocellulose strip, to exploit capillary force to induce a continuous flux of sweat on the sensor platform, ensuring the constant renewal of sample. We could achieve good sensitivity at potentials close to zero by using Prussian Blue as redox mediator, thus avoiding interference from other chemical species present in the complex matrix. The sensing signal was stable and linear over two hours in a concentration range of glucose and lactate between the limit of quantification (32 and 68 nM, respectively) and the upper limit of linearity (3.8 and 50.0 mM, respectively). The device is simple, robust, stable, and can be easily worn without the direct contact of the active part with the skin, making it suitable for simultaneous monitoring of glucose and lactate in human sweat.
32.	Poletti, Fabrizio, et al. (författare) Electrochemical sensing of glucose by chitosan modified graphene oxide 2020 Ingår i: JPhys Materials. - : IOP Publishing. - 2515-7639. ; 3:1 Tidskriftsartikel (refereegranskat)abstract Graphene oxide (GO) coated electrodes provide an excellent platform for enzymatic glucose sensing, induced by the presence of glucose oxidase and an electrochemical transduction. Here, we show that the sensitivity of GO layers for glucose detection redoubles upon blending GO with chitosan (GO+Ch) and increases up to eight times if covalent binding of chitosan to GO (GO-Ch) is exploited. In addition, the conductivity of the composite material GO-Ch is suitable for electrochemical applications without the need of GO reduction, which is generally required for GO based coatings. Covalent modification of GO is achieved by a standard carboxylic activation/amidation approach by exploiting the abundant amino pendants of chitosan. Successful functionalization is proved by comparison with an ad-hoc synthesized control sample realized by using non-activated GO as precursor. The composite GO-Ch was deposited on standard screen-printed electrodes by a drop-casting approach. Comparison with a chitosan-GO blend and with pristine GO demonstrated the superior reliability and efficiency of the electrochemical response for glucose as a consequence of the high number of enzyme binding sites and of the partial reduction of GO during the carboxylic activation synthetic step.
33.	Poletti, Fabrizio, et al. (författare) Graphene-Paper-Based Electrodes on Plastic and Textile Supports as New Platforms for Amperometric Biosensing 2022 Ingår i: Advanced Functional Materials. - : Wiley. - 1616-3028 .- 1616-301X. ; 32:7 Tidskriftsartikel (refereegranskat)abstract The possibility of exfoliating graphite into graphene sheets allows the researchers to produce a material, termed “graphene paper” (G-paper), conductive as graphite but more flexible and processable. G-paper is already used for electronic applications, like conductors, antennas, and heaters, outperforming metal conductors thanks to its high flexibility, lightness, chemical stability, and compatibility with polymeric substrates. Here, the effectiveness in the use of G-paper for the realization of electrodes on flexible plastic substrates and textiles, and their applicability as amperometric sensors are demonstrated. The performance of these devices is compared with commercial platforms made of carbon-based inks, finding that they outperform commercial devices in sensing nicotinamide adenine dinucleotide (NADH), a key molecule for enzymatic biosensing; the electrodes can achieve state-of-the-art sensitivity (107.2 μA mm−1 cm−2) and limit of detection (0.6 × 10−6 m) with no need of additional functionalization. Thanks to this property, the stable deposition of a suitable enzyme, namely lactate dehydrogenase, on the electrode surface is used as a proof of concept of the applicability of this new platform for the realization of a biosensor. The possibility of having a single material suitable for antennas, electronics, and now sensing opens new opportunities for smart fabrics in wearable electronic applications.
34.	Posati, Tamara, et al. (författare) Polydopamine Nanoparticle-Coated Polysulfone Porous Granules as Adsorbents for Water Remediation 2019 Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 4:3, s. 4839-4847 Tidskriftsartikel (refereegranskat)abstract Water purification technologies possibly based on eco-sustainable, low cost, and multifunctional materials are being intensively pursued to resolve the current water scarcity and pollution. In this scenario, polysulfone hollow porous granules (PS-HPGs) prepared from scraps of the industrial production of polysulfone hollow fiber membranes were recently introduced as adsorbents and filtration materials for water and air treatment. Here, we report the functionalization of PS-HPGs with polydopamine (PD) nanoparticles for the preparation of a new versatile and efficient adsorbent material, namely, PSPD-HPGs. The in situ growth of PD under mild alkaline oxidative polymerization allowed us to stably graft PD on polysulfone granules. Enhanced removal efficiency of ofloxacin, an antibiotic drug, with an improvement up to 70% with respect to the pristine PS-HPGs, and removal of Zn(II) and Ni(II) were also observed after PD modification. Remarkably, removal of Cu(II) ions with an efficiency up to 80% was observed for PSPD-HPGs, whereas no adsorption was found for the PD-free precursor. Collectively, these data show that modification with a biocompatible polymer such as PD provides a simple and valuable tool to enlarge the field of application of polysulfone hollow granules for water remediation from both organic and metal cation contaminants.
35.	Quintano, Vanesa, et al. (författare) Long-range selective transport of anions and cations in graphene oxide membranes, causing selective crystallization on the macroscale 2021 Ingår i: Nanoscale Advances. - : Royal Society of Chemistry (RSC). - 2516-0230. ; 3:2, s. 353-358 Tidskriftsartikel (refereegranskat)abstract Monoatomic nanosheets can form 2-dimensional channels with tunable chemical properties, for ion storage and filtering applications. Here, we demonstrate transport of K+, Na+, and Li+ cations and F- and Cl- anions on the centimeter scale in graphene oxide membranes (GOMs), triggered by an electric bias. Besides ion transport, the GOM channels foster also the aggregation of the selected ions in salt crystals, whose composition is not the same as that of the pristine salt present in solution, highlighting the difference between the chemical environment in the 2D channels and in bulk solutions.
36.	Quintano, Vanesa, et al. (författare) Measurement of the conformational switching of azobenzenes from the macro- to attomolar scale in self-assembled 2D and 3D nanostructures 2021 Ingår i: Physical Chemistry Chemical Physics. - : Royal Society of Chemistry (RSC). - 1463-9084 .- 1463-9076. ; 23:20, s. 11698-11708 Tidskriftsartikel (refereegranskat)abstract It is important, but challenging, to measure the (photo)induced switching of molecules in different chemical environments, from solution through thin layers to solid bulk crystals. We compare the cis-trans conformational switching of commercial azobenzene molecules in different liquid and solid environments: polar solutions, liquid polymers, 2D nanostructures and 3D crystals. We achieve this goal by using complementary techniques: optical absorption spectroscopy, femtosecond transient absorption spectroscopy, Kelvin probe force microscopy and reflectance spectroscopy, supported by density functional theory calculations. We could observe the same molecule showing fast switching in a few picoseconds, when studied as an isolated molecule in water, or slow switching in tens of minutes, when assembled in 3D crystals. It is worth noting that we could also observe switching for small ensembles of molecules (a few attomoles), representing an intermediate case between single molecules and bulk structures. This was achieved using Kelvin probe force microscopy to monitor the change of surface potential of nanometric thin 2D islands containing ca. 10(6) molecules each, self-assembled on a substrate. This approach is not limited to azobenzenes, but can be used to observe molecular switching in isolated ensembles of molecules or other nano-objects and to study synergistic molecular processes at the nanoscale.
37.	Samorì, Paolo, et al. (författare) Introduction to 'Chemistry of 2D materials: Graphene and beyond' 2020 Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3372 .- 2040-3364. ; 12:48, s. 24309-24310 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract Paolo Samorì, Xinliang Feng and Vincenzo Palermo introduce the Nanoscale themed collection on ‘Chemistry of 2D materials: graphene and beyond’.
38.	Sanchez, Jaime S., et al. (författare) Versatile electrochemical manufacturing of mixed metal sulfide/N-doped rGO composites as bifunctional catalysts for high power rechargeable Zn–air batteries 2024 Ingår i: Journal of Materials Chemistry A. - 2050-7488 .- 2050-7496. ; 12:20, s. 11945-11959 Tidskriftsartikel (refereegranskat)abstract The development of rechargeable zinc–air batteries requires air cathodes capable of performing both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) with high performance and an extended operational lifespan. Here, we present a cost-effective and versatile electrochemical method for the direct assembly of such electrocatalysts, consisting of nitrogen-doped reduced graphene oxide (NrGO) and mixed transition metal sulfides (NiCoMnSx or NCMS). To this end, we use a small electric bias to electro-deposit both NrGO and NCMS directly on conductive graphene foam, resulting in a perfect porous network and two interpenetrated paths for the easy transport of electrons and ions. The NCMS/ NrGO composite shows one of the highest limiting currents reported so far for a non-noble metal catalyst. Additionally, it exhibits outstanding bifunctional performance for the ORR/OER, superior to both mixed transition metal compounds and noble metals from previous reports. Thus, it serves as a highly efficient air cathode for practical zinc–air batteries featuring high power densities (124 mW cm−2) and long catalyst durability (1560 cycles, around 260 h). We attribute the excellent performance to the synergistic effect between hetero-structured metallic sites and nitrogen dopants. Our approach can be used for preparing efficient zinc–air cathodes on conductive 3D carbon substrates with arbitrary shapes and good performance.
39.	Sanchez Sanchez, Jaime, 1990, et al. (författare) All-Electrochemical Nanofabrication of Stacked Ternary Metal Sulfide/Graphene Electrodes for High-Performance Alkaline Batteries 2022 Ingår i: Small. - : Wiley. - 1613-6810 .- 1613-6829. Tidskriftsartikel (refereegranskat)abstract Energy-storage materials can be assembled directly on the electrodes of a battery using electrochemical methods, this allowing sequential deposition, high structural control, and low cost. Here, a two-step approach combining electrophoretic deposition (EPD) and cathodic electrodeposition (CED) is demonstrated to fabricate multilayer hierarchical electrodes of reduced graphene oxide (rGO) and mixed transition metal sulfides (NiCoMnSx). The process is performed directly on conductive electrodes applying a small electric bias to electro-deposit rGO and NiCoMnSx in alternated cycles, yielding an ideal porous network and a continuous path for transport of ions and electrons. A fully rechargeable alkaline battery (RAB) assembled with such electrodes gives maximum energy density of 97.2 Wh kg−1 and maximum power density of 3.1 kW kg−1, calculated on the total mass of active materials, and outstanding cycling stability (retention 72% after 7000 charge/discharge cycles at 10 A g−1). When the total electrode mass of the cell is considered, the authors achieve an unprecedented gravimetric energy density of 68.5 Wh kg−1, sevenfold higher than that of typical commercial supercapacitors, higher than that of Ni/Cd or lead–acid Batteries and similar to Ni–MH Batteries. The approach can be used to assemble multilayer composite structures on arbitrary electrode shapes.
40.	Sanchez Sanchez, Jaime, 1990, et al. (författare) Electrophoretic coating of LiFePO4/Graphene oxide on carbon fibers as cathode electrodes for structural lithium ion batteries 2021 Ingår i: Composites Science and Technology. - : Elsevier BV. - 0266-3538. ; 208 Tidskriftsartikel (refereegranskat)abstract Carbon fibers (CF), commonly used in the structure of airplanes or cars, can also work as conductive electrodes in “structural batteries” for distributed energy storage. To this aim CF should be chemically functionalized, which is challenging due to their complex geometry and surface. Here, we describe an “all-electrostatic” approach taking advantage of the intrinsic conductivity of CF to coat them with a cathode material composed of LiFePO4 blended with nanosheets of electrochemically exfoliated graphene oxide (EGO). We first achieve electrostatic selfassembly of the nanometric components at the nanoscale, then use Electrophoretic Deposition (EPD) to obtain a uniform, macroscale coating on the fibers. We achieve a LiFePO4 loading >90 wt% featuring good adhesion on the carbon fibers, low degradation upon battery cycling, low charge transfer resistance. The electrode composite outperforms similar state-of-the-art cathode materials when used in Half-Cell vs. Li. Full battery cells using coated CF as cathode and pristine CF as anode yield specific energy density of 222.14 Wh⋅kg? 1 and power density of 0.29 kW⋅kg? 1 with 88.1% capacity retention at 1 C over 300 cycles, compatible with industrial applications of this technique in composites production.
41.	Schwartz, Erik, et al. (författare) "Helter-Skelter-Like" Perylene Polyisocyanopeptides 2009 Ingår i: Chemistry: A European Journal. - : Wiley. - 1521-3765 .- 0947-6539. ; 15:11, s. 2536-2547 Tidskriftsartikel (refereegranskat)abstract We report on a combined experimental and computational investigation on the synthesis and thorough characterization of the structure of perylene-functionalized polyisocyanides. Spectroscopic analyses and extensive molecular dynamics studies revealed a well defined 4, helix in which the perylene molecules form four "helter skelter-like" overlapping pathways along which excitons and electrons can rapidly migrate. The well-defined polymer scaffold stabilized by hydrogen bonding, to which the chromophores are attached, accounts for the precise architectural definition, and molecular stiffness observed for these molecules. Molecular-dynamics studies showed that the chirality present in these polymers is expressed in the formation of stable right-handed helices. The formation of chiral supramolecular structures is further supported by the measured and calculated bisignated Cotton effect. The structural definition of the chromophores aligned in one direction along the backbone is highlighted by the extremely efficient exciton migration rates and charge densities measured with Transient Absorption Spectroscopy.
42.	Scidà, A., et al. (författare) Application of graphene-based flexible antennas in consumer electronic devices 2018 Ingår i: Materials Today. - : Elsevier BV. - 1369-7021 .- 1873-4103. ; 21:3, s. 223-230 Tidskriftsartikel (refereegranskat)abstract We describe the fabrication and characterization of Near-Field Communication (NFC) devices based on highly flexible, carbon-based antennas composed of stacked graphene multilayers. This material features a high value of conductivity (4.20 * 10 5 S/m) comparable to monocrystalline graphite, but is much more flexible and processable. We first studied the replacement of metal with carbon antennas using computer modeling, to select the best design. Then we manufactured several devices to be used according to the communication protocol ISO/IEC 15693. The inductance of the G-paper antennas was tested before and after hundreds of thousands of bending cycles at bending radii of 45 and 90 mm. During bending the self-resonance frequency and inductance peak showed minimal variation and the resistance at 1 MHz changed from 33.09 Ω to 34.18 Ω outperforming standard, commercial metallic antennas. The devices were successfully tested by exchanging data with a smartphone and other commercial NFC readers, matching the performance of standard, commercial metallic antennas. The graphene antennas could be deposited on different standard polymeric substrates or on textiles. Smart cards, flexible NFC tags and wearable NFC bracelets were prepared in this way to be used in electronic keys, business cards and other typical NFC applications.
43.	Sun, Jinhua, 1987, et al. (författare) Controllable Coating Graphene Oxide and Silanes on Cu Particles as Dual Protection for Anticorrosion 2023 Ingår i: ACS Applied Materials & Interfaces. - 1944-8252 .- 1944-8244. ; 15:32, s. 38857-38866 Tidskriftsartikel (refereegranskat)abstract Although two-dimensional nanosheets like graphene could be ideal atomic coatings to prevent corrosion, it is still controversial whether they are actually effective due to the presence of parasitic effects such as galvanic corrosion. Here, we reported a reduced graphene oxide (RGO) coating strategy to protect sintered Cu metal powders from corrosion by addressing the common galvanic corrosion issue of graphene. A layer of silane molecules, namely, (3-aminopropyl)triethoxysilane (APTES), is deposited between the surface of Cu particles and the graphene oxide (GO), acting as a primer to enhance adhesion and as an insulating interlayer to prevent the direct contact of the Cu with conductive RGO, mitigating the galvanic corrosion. Due to this core−shell coating, the RGO uniformly distributes in the Cu matrix after sintering, avoiding aggregation of RGO, which takes place in conventional GO-Cu composites. The dual coating of GO and silane results in bulk samples with improved anticorrosion properties, as demonstrated by galvanostatic polarization tests using Tafel analysis. Our development not only provides an efficient synthesis method to controllably coat GO on the surface of Cu but also suggests an alternative strategy to avoid the galvanic corrosion effect of graphene to improve the anticorrosion performance of metal.
44.	Sun, Jinhua, 1987, et al. (författare) Covalent Organic Framework (COF-1) under High Pressure 2020 Ingår i: Angewandte Chemie - International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 59:3, s. 1087-1092 Tidskriftsartikel (refereegranskat)abstract COF-1 has a structure with rigid 2D layers composed of benzene and B3O3 rings and weak van der Waals bonding between the layers. The as-synthesized COF-1 structure contains pores occupied by solvent molecules. A high surface area empty-pore structure is obtained after vacuum annealing. High-pressure XRD and Raman experiments with mesitylene-filled (COF-1-M) and empty-pore COF-1 demonstrate partial amorphization and collapse of the framework structure above 12–15 GPa. The ambient pressure structure of COF-1-M can be reversibly recovered after compression up to 10–15 GPa. Remarkable stability of highly porous COF-1 structure at pressures at least up to 10 GPa is found even for the empty-pore structure. The bulk modulus of the COF-1 structure (11.2(5) GPa) and linear incompressibilities (k[100]=111(5) GPa, k[001]=15.0(5) GPa) were evaluated from the analysis of XRD data and cross-checked against first-principles calculations. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
45.	Sun, Jinhua, 1987, et al. (författare) Critical Role of Functional Groups Containing N, S, and O on Graphene Surface for Stable and Fast Charging Li-S Batteries 2021 Ingår i: Small. - : Wiley. - 1613-6810 .- 1613-6829. ; 17:17 Tidskriftsartikel (refereegranskat)abstract Lithium‐sulfur (Li‐S) batteries are considered one of the most promising energy storage technologies, possibly replacing the state‐of‐the‐art lithium‐ion (Li‐ion) batteries owing to their high energy density, low cost, and eco‐compatibility. However, the migration of high‐order lithium polysulfides (LiPs) to the lithium surface and the sluggish electrochemical kinetics pose challenges to their commercialization. The interactions between the cathode and LiPs can be enhanced by the doping of the carbon host with heteroatoms, however with relatively low doping content (<10%) in the bulk of the carbon, which can hardly interact with LiPs at the host surface. In this study, the grafting of versatile functional groups with designable properties (e.g., catalytic effects) directly on the surface of the carbon host is proposed to enhance interactions with LiPs. As model systems, benzene groups containing N/O and S/O atoms are vertically grafted and uniformly distributed on the surface of expanded reduced graphene oxide, fostering a stable interface between the cathode and LiPs. The combination of experiments and density functional theory calculations demonstrate improvements in chemical interactions between graphene and LiPs, with an enhancement in the electrochemical kinetics, power, and energy densities.
46.	Sun, Jinhua, 1987, et al. (författare) Real-time imaging of Na+ reversible intercalation in "Janus" graphene stacks for battery applications 2021 Ingår i: Science advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 7:22 Tidskriftsartikel (refereegranskat)abstract Sodium, in contrast to other metals, cannot intercalate in graphite, hindering the use of this cheap, abundant element in rechargeable batteries. Here, we report a nanometric graphite-like anode for Na+ storage, formed by stacked graphene sheets functionalized only on one side, termed Janus graphene. The asymmetric functionalization allows reversible intercalation of Na+, as monitored by operando Raman spectroelectrochemistry and visualized by imaging ellipsometry. Our Janus graphene has uniform pore size, controllable functionalization density, and few edges; it can store Na+ differently from graphite and stacked graphene. Density functional theory calculations demonstrate that Na+ preferably rests close to -NH2 group forming synergic ionic bonds to graphene, making the interaction process energetically favorable. The estimated sodium storage up to C6.9Na is comparable to graphite for standard lithium ion batteries. Given such encouraging Na+ reversible intercalation behavior, our approach provides a way to design carbon-based materials for sodium ion batteries.
47.	Sun, Yue, et al. (författare) Surface chemistry and structure manipulation of graphene-related materials to address the challenges of electrochemical energy storage 2023 Ingår i: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1364-548X .- 1359-7345. ; 59:18, s. 2571-2583 Tidskriftsartikel (refereegranskat)abstract Energy storage devices are important components in portable electronics, electric vehicles, and the electrical distribution grid. Batteries and supercapacitors have achieved great success as the spearhead of electrochemical energy storage devices, but need to be further developed in order to meet the ever-increasing energy demands, especially attaining higher power and energy density, and longer cycling life. Rational design of electrode materials plays a critical role in developing energy storage systems with higher performance. Graphene, the well-known 2D allotrope of carbon, with a unique structure and excellent properties has been considered a “magic” material with its high energy storage capability, which can not only aid in addressing the issues of the state-of-the-art lithium-ion batteries and supercapacitors, but also be crucial in the so-called post Li-ion battery era covering different technologies, e.g., sodium ion batteries, lithium-sulfur batteries, structural batteries, and hybrid supercapacitors. In this feature article, we provide a comprehensive overview of the strategies developed in our research to create graphene-based composite electrodes with better ionic conductivity, electron mobility, specific surface area, mechanical properties, and device performance than state-of-the-art electrodes. We summarize the strategies of structure manipulation and surface modification with specific focus on tackling the existing challenges in electrodes for batteries and supercapacitors by exploiting the unique properties of graphene-related materials.
48.	Tunioli, Francesca, et al. (författare) Adsorption of emerging contaminants by graphene related materials and their alginate composite hydrogels 2023 Ingår i: Journal of Environmental Chemical Engineering. - : Elsevier BV. - 2213-3437 .- 2213-2929. ; 11:2 Tidskriftsartikel (refereegranskat)abstract Graphene nanosheets and nanoplatelets -alginate composite hydrogels were prepared by ionic gelation and the resulting gel beads were exploited for the removal of a mixture of eight selected emerging contaminants (ECs) in tap water, including bisphenol A, ofloxacin and diclofenac. The role of graphene related materials (GRM) on the gel bead structure, adsorption selectivity, kinetic, mechanism, and efficiency was investigated. Combined Scanning Electron Microscopy (SEM) and confocal Raman microscopy mapping showed a porous structure with pore size in the range of 100–200 µm and a homogeneous distribution of graphene nanosheets or nanoplatelets at the pores surface. The adsorption kinetic of GRM was much faster than that of granular activated carbon (GAC), the industrial sorbent benchmark, with removal capacity of ofloxacin from 2.9 to 4.3 times higher. A maximum adsorption capacity of 178 mg/g for rhodamine B was estimated by adsorption isotherm studies for reduced graphene oxide-based beads (a value comparable to that of powered activated carbon). Regeneration test performed on saturated beads by washing with EtOH, and subsequent reiterated reuses, showed no loss of adsorption performance up to the fourth reuse cycle.
49.	Tunioli, Francesca, et al. (författare) Chemical Tailoring of β-Cyclodextrin-Graphene Oxide for Enhanced Per- and Polyfluoroalkyl Substances (PFAS) Adsorption from Drinking Water 2023 Ingår i: Chemistry - A European Journal. - 1521-3765 .- 0947-6539. ; 29:60 Tidskriftsartikel (refereegranskat)abstract We report on the synthesis of β-cyclodextrin (βCD) modified graphene oxide (GO) nanosheets, having different sized alkyl linkers (GO-Cn-βCD) and their exploitation as sorbent of per- and polyfluoroalkyl substances (PFAS) from drinking water. βCD were functionalized with a pending amino group, and the resulting precursors grafted to GO nanosheets by epoxide ring opening reaction. Loading of βCD units in the range 12 %–36 % was estimated by combined XPS and elemental analysis. Adsorption tests on perfluorobutanoic acid (PFBA), a particularly persistent PFAS selected as case study, revealed a strong influence of the alkyl linker length on the adsorption efficiency, with the hexyl linker derivative GO-C6-βCD outperforming both pristine GO and granular activated carbon (GAC), the standard sorbent benchmark. Molecular dynamic simulations ascribed this evidence to the favorable orientation of the βCD unit on the surface of GO which enables a strong contaminant molecules retention.
50.	Valorosi, Filippo, et al. (författare) Graphene and related materials in hierarchical fiber composites: Production techniques and key industrial benefits 2020 Ingår i: Composites Science and Technology. - : Elsevier BV. - 0266-3538. ; 185 Forskningsöversikt (refereegranskat)abstract Fiber-reinforced composites (FRC) are nowadays one of the most widely used class of high-tech materials. In particular, sporting goods, cars and the wings and fuselages of airplanes are made of carbon fiber reinforced composites (CFRC). CFRC are mature commercial products, but are still challenging materials. Their mechanical and electrical properties are very good along the fiber axis, but can be very poor perpendicular to it; interfacial interactions have to be tailored for specific applications to avoid crack propagation– and delamination; fiber production includes high-temperature treatments of adverse environmental impact, leading to high costs. Recent research work shows that the performance of CFRC can be improved by addition of graphene or related 2-dimensional materials (GRM). Graphene is a promising additive for CFRC because: 1) Its all-carbon aromatic structure is similar to the one of carbon fiber (CF). 2) Its 2-dimensional shape, high aspect ratio, high flexibility and mechanical strength allow it to be used as a coating on the surface of fiber, or as a mechanical/electrical connection between different fiber layers. 3) Its tunable surface chemistry allows its interaction to be enhanced with either the fiber or the polymer matrix used in the composite and 4) in contrast to carbon fibers or nanotubes, it is easily produced on a large scale at room temperature, without metal catalysts. Here, we summarize the key strategic advantages that could be obtained in this way, and some of the recent results that have been obtained in this field within the Graphene Flagship project and worldwide.

Skapa referenser, mejla, bekava och länka

Länka till träfflistan

Träfflista för sökning "WFRF:(Palermo Vincenzo) "

Avgränsa träffmängd

År