| 1. |
- Aderne, Rian E., et al.
(författare)
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On the energy gap determination of organic optoelectronic materials : the case of porphyrin derivatives
- 2022
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Ingår i: Materials Advances. - : Royal Society of Chemistry. - 2633-5409. ; :3, s. 1791-1803
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Tidskriftsartikel (refereegranskat)abstract
- The correct determination of the ionization potential (IP) and electron affinity (EA) as well as the energy gap is essential to properly characterize a series of key phenomena related to the applications of organic semiconductors. For example, energy offsets play an essential role in charge separation in organic photovoltaics. Yet there has been a lot of confusion involving the real physical meaning behind those quantities. Experimentally the energy gap can be measured by direct techniques such as UV-Vis absorption, or indirect techniques such as cyclic voltammetry (CV). Another spectroscopic method is the Reflection Electron Energy Loss Spectroscopy (REELS). Regarding data correlation, there is little consensus on how the REELS' energy gap can be interpreted in light of the energies obtained from other methodologies such as CV, UV-Vis, or photoemission. In addition, even data acquired using those traditional techniques has been misinterpreted or applied to derive conclusions beyond the limits imposed by the physics of the measurement. A similar situation also happens when different theoretical approaches are used to assess the energy gap or employed to explain outcomes from experiments. By using a set of porphyrin derivatives as model molecules, we discuss some key aspects of those important issues. The peculiar properties of these porphyrins demonstrate that even straightforward measurements or calculations performed in a group of very similar molecules need a careful interpretation of the outcomes. Differences up to 660 meV (similar to 190 meV) are found comparing REELS (electrochemical) measurements with UV-Vis energy gaps, for instance. From the theoretical point of view, a reasonable agreement with electrochemical measurements of the IP, EA, and the gap of the porphyrins is only obtained when the calculations involve the full thermodynamics of the redox processes. The purpose of this work is to shed light on the differences and similarities of those aforementioned characterization methods and provide some insight that might help one to develop a critical analysis of the different experimental and theoretical methodologies.
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| 2. |
- Allushi, Andrit, et al.
(författare)
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Hydroxide conducting BAB triblock copolymers tailored for durable high-performance anion exchange membranes
- 2023
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Ingår i: Materials Advances. - 2633-5409. ; 4:17, s. 3733-3745
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Tidskriftsartikel (refereegranskat)abstract
- Well-designed block copolymers with a controlled co-continuous microphase morphology can be applied as efficient anion exchange membranes (AEMs) for fuel cells and water electrolyzers. In the present work, we have prepared and studied a series of BAB triblock copolymers consisting of a central cationic polyfluorene A block with flanking hydrophobic polystyrene B blocks, where the fluorene units of the A block carried double pairs of piperidinium cations via flexible hexyl spacer chains. First, a polyfluorene tethered with bromohexyl chains was prepared by superacid-mediated polyhydroxyalkylation, and then modified to produce a bi-directional macroinitiator for atom transfer radical polymerization (ATRP). Next, ATRP of styrene was carried out to form BAB triblock copolymers with different lengths of the B blocks. Finally, the polyfluorene block was densely functionalized with piperidinium cations by Menshutkin reactions. Small angle X-ray scattering of block copolymer AEMs indicated the presence of both block copolymer phase domains (d~15 nm) and ionic clusters (d~6 nm). Atomic force microscopy showed clearly phase-separated morphologies with seemingly well-connected hydrophilic nanophase domains for ion transport. The AEMs reached hydroxide conductivities up to 161 mS cm-1 at 80 ºC. Moreover, the AEMs decomposed only above 250 °C and possessed excellent alkaline stability with no degradation detected by 1H NMR analysis after storage in 2 M aq. NaOH, at 90 °C during 672 h. Notably, the current block copolymer AEMs showed higher alkaline stability and hydroxide conductivity compared to AEMs based on corresponding statistical copolymers.
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| 3. |
- Bartkowska, Aleksandra, et al.
(författare)
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Biodegradable porous FeMn(-xAg) alloys: assessment of cytocompatibility, mechanical, magnetic and antibiofilm properties
- 2023
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Ingår i: Materials Advances. - : Royal Society of Chemistry (RSC). - 2633-5409. ; 4:2, s. 616-630
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Tidskriftsartikel (refereegranskat)abstract
- In this work, porous FeMn(-xAg) alloys are fabricated through powder metallurgy methods. The effects of porosity and Ag addition on the microstructure, biodegradability, magnetic and mechanical properties of the alloys are investigated. Studies on the cytocompatibility, inflammatory cytokine response and antibacterial effect are also conducted. The fabricated alloys exhibit a macro- and nanoporous structure, with uniformly distributed silver particles. The biodegradability tests reveal that the release of Mn to the Hank's solution is higher than that of Fe, without significant differences between the alloys. The degradation products consist mainly of Fe, Mn, O and compounds enriched in Ca, P and Cl. As-sintered alloys show a low saturation magnetization value (below 1 emu g−1), which does not increase significantly with immersion time. The results on biocompatibility indicate that all tested alloys are non-cytotoxic, but the addition of Ag might interfere with cell proliferation. However, the ions released by the FeMn(-xAg) alloys do not induce an inflammatory response in macrophages. The obtained results on microbiological interactions reveal that although no significant bactericidal effect is observed at 4 h between FeMn control and FeMn-5Ag, a significant reduction in the total biofilm biomass of both live and dead bacteria is observed after 24 h in Ag containing FeMn-5Ag surfaces.
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| 4. |
- Birdsong, Björn K., et al.
(författare)
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Flexible and fire-retardant silica/cellulose aerogel using bacterial cellulose nanofibrils as template material
- 2024
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Ingår i: Materials Advances. - : Royal Society of Chemistry. - 2633-5409. ; 5:12, s. 5041-5051
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Tidskriftsartikel (refereegranskat)abstract
- This study explores the possibility of using various silsesquioxane precursors such as (3-aminopropyl) triethoxysilane (APTES), methyltrimethoxysilane (MTMS), and tetraethyl orthosilicate (TEOS) to produce silsesquioxane-bacterial cellulose nanofibre (bCNF) aerogels. Each precursor allowed to customize the aerogel properties, leading to unique properties suitable for various applications requiring lightweight insulative materials. When utilizing APTES as the silsesquioxane precursor, an aerogel capable of over 90% recovery after compression was formed, making them suitable for flexible applications. When MTMS was used as the precursor, the aerogel retained some compression recovery (80%) but had the added property of superhydrophobicity with a contact angle over 160° due to the presence of CH3 functional groups, enabling water-repellence. Finally, TEOS allowed for excellent thermal insulative properties with a low Peak Heat Release Rate (PHRR), making it a promising candidate for fire-resistant applications. The customization of these aerogel materials was attributed to a combination of the chemical composition of the silsesquioxane precursors and the morphology of the coated bacterial cellulose nanofibres (bCNF), such as CH3 groups found in MTMS enabled for superhydrophobicity. Differences in morphology, such as uniform and smooth silsesquioxane coatings when using APTES or a “pearl-necklace” morphology using TEOS, enabled either compression recovery and flexibility or low thermal conduction. This investigation of silsesquioxane-bCNF provides a good understanding of the importance of the choice of precursor effect on insulating aerogel properties.
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| 5. |
- Dahlqvist, Martin, 1982-, et al.
(författare)
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Chemical order or disorder - a theoretical stability expose for expanding the compositional space of quaternary metal borides
- 2022
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Ingår i: Materials Advances. - : Royal Society of Chemistry. - 2633-5409. ; 3:6, s. 2908-2917
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Tidskriftsartikel (refereegranskat)abstract
- Inspired by the recent discovery of Ti4MoSiB2, a quaternary phase with out-of-plane chemical order that we denote as o-MAB, we perform an extensive first-principles study to explore the attained chemical order and disorder (solid-solution) upon metal alloying of M(5)AB(2) (T2 phases), with M from Groups 3 to 9 and A = Al, Si, P, Ga, and Ge. We show that the attainable chemistries of T2 can be significantly expanded and predict 35 chemically ordered o-MAB phases and 121 solid solutions of an MM-4 AB(2) stoichiometry. The possibility of realizing o-MAB or solid solution MAB phases combined with multiple elemental combinations previously not observed in these borides suggests an increased property tuning potential. Furthermore, five ternary T2 phases, yet to be synthesized, are also predicted to be stable.
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| 6. |
- de Bruin-Dickason, Caspar, et al.
(författare)
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Valorisation of used lithium-ion batteries into nanostructured catalysts for green hydrogen from boranes
- 2020
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Ingår i: Materials Advances. - : Royal Society of Chemistry (RSC). - 2633-5409. ; 1:7, s. 2279-2285
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Tidskriftsartikel (refereegranskat)abstract
- Cobalt-based Li-ion batteries are produced globally on a massive scale, but most are discarded to landfill at the end of their useful lifetime. In this work, an efficient cobalt catalyst for the hydrolysis of sodium borohydride to dihydrogen was prepared from lithium ion battery waste, providing a second life for valuable minerals. This material is composed of a mixed metal cobalt-aluminium oxide supported on graphene, as elucidated by a combined FTIR, Raman, SEM, scanning transmission electron microscopy with electron energy loss spectroscopy (STEM-EELS) and energy-dispersive X-ray spectroscopy (EDS) study. The obtained metal oxide material, which exhibits an average oxidation state for Co of 2.45, is a languid catalyst at room temperature, but rapid hydrogen production of up to 49 L(H-2) min(-1) g(-1)(Co) was observed in catalytic runs heated to 70 degrees C. This carbon-supported cobalt catalyst is competitive with designed cobalt nanostructured catalysts prepared from pure precursors. This work is illustrative of the opportunities which arise when e-waste is utilised as a mineral resource within the scope of a circular economy.
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| 7. |
- Doppelbauer, David, et al.
(författare)
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P-type cobaltite oxide spinels enable efficient electrocatalytic oxygen evolution reaction
- 2021
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Ingår i: Materials Advances. - : Royal Society of Chemistry. - 2633-5409. ; 2:16, s. 5494-5500
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Tidskriftsartikel (refereegranskat)abstract
- Currently, energy-efficient electrocatalytic oxygen evolution from water involves the use of noble metal oxides. Here, we show that highly p-conducting zinc cobaltite spinel Zn1.2Co1.8O3.5 offers an enhanced electrocatalytic activity for oxygen evolution. We refer to previous studies on sputtered Zn-Co spinels with optimized conductivity for implementation as (p-type) transparent conducting oxides. Based on that, we manufacture off-stoichiometric conducting p-spinel catalytic anodes on tetragonal Ti, Au-Ti and hexagonal Al-doped ZnO carriers and report the evolution of O-2 at Tafel slopes between 40.5 and 48 mV dec(-1) and at overpotentials between 0.35 and 0.43 V (at 10 mA cm(-2)). The anodic stability, i.e., 50 h of continuous O-2 electrolysis in 1 M KOH, suggests that increasing the conductivity is advantageous for electrolysis, particularly for reducing the ohmic losses and ensuring activity across the entire surface. We conclude by pointing out the merits of improving p-doping in Zn-Co spinels by optimized growth on a tetragonal Ti-carrier and their application as dimension-stable 3d-metal anodes.
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| 8. |
- Etman, Ahmed, et al.
(författare)
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Fabrication of Mo1.33CTz (MXene)-cellulose freestanding electrodes for supercapacitor applications
- 2021
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Ingår i: Materials Advances. - : ROYAL SOC CHEMISTRY. - 2633-5409. ; 2:2, s. 743-753
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Tidskriftsartikel (refereegranskat)abstract
- MXenes are two-dimensional (2D) transition metal carbides/nitrides with high potential for energy storage devices owing to their high flexibility, conductivity and specific capacitance. However, MXene films tend to suffer from diffusion limitation of ions within the film, and thus their thickness is commonly reduced to a few micrometers (mass loadings <1 mg cm(-2)). Herein, a straightforward one-step protocol for synthesizing freestanding Mo1.33CTz-cellulose composite electrodes with high MXene loading is reported. By varying the amount of the cellulose content, a high gravimetric capacitance (up to 440 F g(-1) for 45 wt% cellulose content, <similar to>5.9 mu m thick film) and volumetric capacitance (up to 1178 F cm(-3) for 5 wt% cellulose content, similar to 4.8 mu m thick film) is achieved. These capacitance values are superior to those for the pristine MXene film, of a similar MXene loading (1.56 mg cm(-2), similar to 4.2 mu m thick film), delivering values of about 272 F g(-1) and 1032 F cm(-3). Interestingly, the Mo1.33CTz-cellulose composite electrodes display an outstanding capacitance retention (similar to 95%) after 30000 cycles, which is better than those reported for other Mo1.33CTz-based electrodes. Furthermore, the presence of cellulose inside a thick composite electrode (similar to 26 mu m, MXene loading 5.2 mg cm(-2)) offers a novel approach for opening the structure during electrochemical cycling, with resulting high areal capacitance of about 1.4 F cm(-2). A symmetric device of Mo1.33CTz-cellulose electrodes featured a long lifespan of about 35000 cycles and delivered a device capacitance up to 95 F g(-1). The superior performance of the Mo1.33CTz-cellulose electrodes in terms of high gravimetric, volumetric, and areal capacitances, long lifespan, and promising rate capability, paves the way for their use in energy storage devices.
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| 9. |
- Gaio, Servane, et al.
(författare)
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Nanoceria-nanocellulose hybrid materials for delayed release of antibiotic and anti-inflammatory medicines
- 2022
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Ingår i: Materials Advances. - : Royal Society of Chemistry. - 2633-5409. ; 3:19, s. 7228-7234
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Tidskriftsartikel (refereegranskat)abstract
- A novel nanoceria-nanocellulose hybrid material has been developed and evaluated as a potential drug delivery system. Crystalline nanoceria was synthesized in situ in the nanocellulose to obtain a homogenous distribution without extensive particle aggregation. The hybrid materials were loaded with two antibiotic drugs, triclosan and ampicillin, and one anti-inflammatory drug, diclofenac. The bacteriostatic effect on the gram-negative bacteria Escherichia coli was evaluated for the hybrid materials containing triclosan and ampicillin. The nanoceria-nanocellulose hybrid displayed a better retention of ampicillin than triclosan in the disc diffusion test, which is likely due to the presence of the carboxylic acid group in ampicillin that has better affinity for ceria compared to the phenolic group in triclosan. However, drug release studies in solution revealed rapid release of ampicillin and diclofenac, indicative of outer-sphere complexes between ceria and the drugs.
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| 10. |
- Garakani, Sadaf Saeedi, et al.
(författare)
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Template-synthesis of a poly(ionic liquid)-derived Fe1−xS/nitrogen-doped porous carbon membrane and its electrode application in lithium–sulfur batteries
- 2021
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Ingår i: Materials Advances. - : Royal Society of Chemistry (RSC). - 2633-5409. ; 2:15, s. 5203-5212
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Tidskriftsartikel (refereegranskat)abstract
- This study deals with the facile synthesis of Fe1−xS nanoparticle-containing nitrogen-doped porous carbon membranes (denoted as Fe1−xS/N-PCMs) via vacuum carbonization of hybrid porous poly(ionic liquid) (PIL) membranes, and their successful use as a sulfur host material to mitigate the shuttle effect in lithium–sulfur (Li–S) batteries. The hybrid porous PIL membranes as the sacrificial template were prepared via ionic crosslinking of a cationic PIL with base-neutralized 1,1′-ferrocenedicarboxylic acid, so that the iron source was molecularly incorporated into the template. The carbonization process was investigated in detail at different temperatures, and the chemical and porous structures of the carbon products were comprehensively analyzed. The Fe1−xS/N-PCMs prepared at 900 °C have a multimodal pore size distribution with a satisfactorily high surface area and well-dispersed iron sulfide nanoparticles to physically and chemically confine the LiPSs. The sulfur/Fe1−xS/N-PCM composites were then tested as electrodes in Li–S batteries, showing much improved capacity, rate performance and cycle stability, in comparison to iron sulfide-free, nitrogen-doped porous carbon membranes.
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