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1.	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.
2.	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.
3.	Çlnar, Mustafa Neşet, et al. (författare) Toward Optimized Charge Transport in Multilayer Reduced Graphene Oxides 2022 Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 22:6, s. 2202-2208 Tidskriftsartikel (refereegranskat)abstract In the context of graphene-based composite applications, a complete understanding of charge conduction in multilayer reduced graphene oxides (rGO) is highly desirable. However, these rGO compounds are characterized by multiple and different sources of disorder depending on the chemical method used for their synthesis. Most importantly, the precise role of interlayer interaction in promoting or jeopardizing electronic flow remains unclear. Here, thanks to the development of a multiscale computational approach combining first-principles calculations with large-scale transport simulations, the transport scaling laws in multilayer rGO are unraveled, explaining why diffusion worsens with increasing film thickness. In contrast, contacted films are found to exhibit an opposite trend when the mean free path becomes shorter than the channel length, since conduction becomes predominantly driven by interlayer hopping. These predictions are favorably compared with experimental data and open a road toward the optimization of graphene-based composites with improved electrical conduction.
4.	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.
5.	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.
6.	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.
7.	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.
8.	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.
9.	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.
10.	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.
11.	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.
12.	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.
13.	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.
14.	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.
15.	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.
16.	Oberhauser, Werner, et al. (författare) Glycerol to lactic acid conversion by NHC-stabilized iridium nanoparticles 2018 Ingår i: Journal of Catalysis. - : Elsevier BV. - 0021-9517 .- 1090-2694. ; 368, s. 298-305 Tidskriftsartikel (refereegranskat)abstract Hydrogen reduction of an Ir(I) complex featured by a bulky N-heterocyclic carbene (NHC) ligand in dichloromethane gave small-sized (1.8 nm) Ir nanoparticles (NPs) decorated with NHC ligands (IrNHC). 1,4-Dioxane solutions of the latter particles were successfully applied to convert glycerol into lactic acid in the presence of NaOH (i.e. 1 mol equivalent with respect to glycerol). IrNHC showed an atom-related TOF value of almost 104 h−1, an almost exclusive formation of liquid reaction products, a high selectivity for lactic acid (93.0%) and a complete recyclability in air atmosphere. Attempts to synthesize analogous NHC-stabilized Ir NPs on a high surface area carbon support (CK) by reducing the same Ir(I) precursor, supported onto CK, prior to the hydrogen reduction in water, gave almost naked CK-supported Ir NPs (1.4 nm). Their catalytic activity tested for the same reaction in water as reaction medium, exhibited much lower catalytic activity (4 × 103 h−1), a lower percentage of liquid reaction products (i.e. 27.0% of the converted glycerol) and a lower selectivity for lactic acid compared to IrNHC.
17.	Parkula, Vitaliy, et al. (författare) Harnessing Selectivity and Sensitivity in Electronic Biosensing: A Novel Lab-on-Chip Multigate Organic Transistor 2020 Ingår i: Analytical Chemistry. - : AMER CHEMICAL SOC. - 0003-2700 .- 1520-6882. ; 92:13, s. 9330-9337 Tidskriftsartikel (refereegranskat)abstract Electrolyte gated organic transistors can operate as powerful ultrasensitive biosensors, and efforts are currently devoted to devising strategies for reducing the contribution of hardly avoidable, nonspecific interactions to their response, to ultimately harness selectivity in the detection process. We report a novel lab-on-a-chip device integrating a multigate electrolyte gated organic field-effect transistor (EGOFET) with a 6.5 mu L microfluidics set up capable to provide an assessment of both the response reproducibility, by enabling measurement in triplicate, and of the device selectivity through the presence of an internal reference electrode. As proof-of-concept, we demonstrate the efficient operation of our pentacene based EGOFET sensing platform through the quantification of tumor necrosis factor alpha with a detection limit as low as 3 pM. Sensing of inflammatory cytokines, which also include TNF alpha, is of the outmost importance for monitoring a large number of diseases. The multiplexable organic electronic lab-on-chip provides a statistically solid, reliable, and selective response on microliters sample volumes on the minutes time scale, thus matching the relevant key-performance indicators required in point-of-care diagnostics.
18.	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.
19.	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.
20.	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.
21.	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.
22.	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.
23.	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.
24.	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.
25.	Vulcano, Fabio, et al. (författare) Dopamine-functionalized graphene oxide as a high-performance material for biosensing 2020 Ingår i: 2D Materials. - : IOP Publishing. - 2053-1583. ; 7:2 Tidskriftsartikel (refereegranskat)abstract We describe a nanocomposite material for the electrochemical detection of beta-nicotinamide adenine dinucleotide (NADH), a coenzyme involved in redox reactions of all living cells and in the detection of many organic species by electrochemical biosensors. The composite is made of nanosheets of electrochemically exfoliated graphene oxide (EGO) covalently functionalized with dopamine (DP) molecules. The EGODP material finally obtained is rich of 1,2-dihydroxyphenyl moieties and is able to detect NADH at a particular low potential value with higher sensitivity with respect to pristine EGO. To study the effectiveness of 1,2-dihydroxyphenyl moieties in inducing electrocatalytic oxidation of NADH, we combined standard voltammetric techniques with UV-Vis absorption spectroelectrochemistry, which allowed us to measure the variations in composition occurring at the electrode vertical bar solution interface, i.e. to measure the consumption rate of NADH. Spectroelectrochemical tests performed by polarising the electrode at a fixed potential value were finally used to compare the performance of EGODP with both EGO and EGO-DP blend (MIX) for the detection of NADH. The covalently functionalized EGO (EGODP) shows sensitivity to NADH up to 300 M-1, around 180 % and 140 % better than either pristine EGO or MIX, respectively.
26.	Xia, Zhenyuan, 1983, et al. (författare) Dispersion Stability and Surface Morphology Study of Electrochemically Exfoliated Bilayer Graphene Oxide 2019 Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 123:24, s. 15122-15130 Tidskriftsartikel (refereegranskat)abstract During the last decade, electrochemical exfoliation of graphite has aroused great interest from both academia and industry for mass production of graphene sheets. Electrochemically exfoliated graphene oxide (EGO) features a much better tunability than chemically EGO, or even than graphene obtained with ultrasonic exfoliation. Chemical and electrical properties of EGO can be modified extensively, thanks to its step-controllable oxidation process, varying the electrolytes and/or the applied potential. It is thus possible, using tunable electrochemical oxidation, to produce low-defect EGO sheets, featuring both good electric conductivity and good dispersibility in common solvents (e.g., acetonitrile or isopropanol). This greatly facilitates its application in several fields, for example, in flexible electronics. In this work, we correlate the dispersion behavior of EGO with its chemical properties using the relative Hansen solubility parameter, zeta potential values, X-ray photoemission spectroscopy, and Raman analysis. A surface morphology study by atomic force microscopy and transmission electron microscopy analyses also reveals that EGO sheets are multiple structures of (partially oxidized) graphene bilayers. Conductive EGO films could be easily prepared by vacuum filtration on different substrates, obtaining electrical conductivity values of up to ∼104 S/m with no need for further reduction procedures.
27.	Zambianchi, Massimo, et al. (författare) Graphene oxide-polysulfone hollow fibers membranes with synergic ultrafiltration and adsorption for enhanced drinking water treatment 2022 Ingår i: Journal of Membrane Science. - : Elsevier BV. - 1873-3123 .- 0376-7388. ; 658 Tidskriftsartikel (refereegranskat)abstract Polysulfone-graphene oxide hollow fiber membranes (PSU-GO HFs) with simultaneous adsorption and ultrafiltration capabilities are herein described and proposed for enhanced and simplified Point-of-Use (POU) drinking water purification. The PSU-GO HFs were prepared by phase inversion extrusion by a customized semi-industrial plant and their morphology, surface properties, and porosity were investigated by combined Scanning Electron Microscopy (SEM), contact angle and Raman confocal microscopy, in relation to different GO:PSU ratios (1–5% w/w GO vs PSU) and to the final adsorption-ultrafiltration properties. Filtration modules of PSU-GO HFs of filtering surface (FS) in the range 0,015–0,28 m2 showed same ultrafiltration capability of PSU-HF standard filters. Synergic adsorption properties were demonstrated by studying the adsorption maximum capacity of ciprofloxacin antibiotic (CIPRO) vs GO ratio in dead end in-out configuration, the standard configuration used for PSU HFs commercial modules. Loading of 3,5% GO vs PSU was selected as case study, representing the best compromise between performance and GO nanofiller amount. Heavy metals (Pb, Cu and Cr(III)) and polyfluoroalkyl substances (PFAS) removal capabilities from tap water were competitive and in some cases outperformed Granular Activated Carbon (GAC), the standard industrial sorbent. Ciprofloxacin removal from tap water was also under real operational conditions. Moreover, release of GO from working PSU-GO modules was excluded by Surface Enhanced Raman Spectroscopy (SERS) analysis of treated water having the state-of-the-art limit of quantification of 0.1 μg/L for GO nanosheets.

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