Materials Today Chemistry

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ISSN : 2468-5194
Published by: Elsevier BV (10.1016)
Total articles ≅ 495
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M. Mgolombane, S. Majodina, O.M. Bankole, ,
Published: 1 June 2021
Materials Today Chemistry, Volume 20; doi:10.1016/j.mtchem.2021.100446

Abstract:
ZnO (Z-1), Co-doped ZnO (Z-2), and Co-doped ZnO/rGO (Z-3) nanocomposites are successfully synthesized using a solvothermal method and investigated toward the photoreduction of CO2 to CH3OH. The as-prepared ZnO (Z-1), Co-doped ZnO (Z-2), and Co-doped ZnO/rGO (Z-3) nanomaterials are characterized by a range of spectroscopic, imaging, and thermal techniques, including X-ray diffraction, X-ray photoelectron spectroscopy, energy-dispersive X-ray analysis, thermogravimetry analysis-differential thermal calorimetry, UV–Vis diffuse reflectance spectroscopy, scanning electron microscopy, and transmission electron micrograph. It was found that Z-3 presented a higher CH3OH rate of 30.1 μmol/g compared with Z-2 (27.3 μmol/g) and Z-1 (7.5 μmol/g). Enhanced catalytic activity of Z-3 over other samples was because of the combined effect of the amount of Co, reduced graphene (rGO), and surface area (10.62 m2/g). Theoretical calculation revealed that photocatalytic activity has some relationship with the ELUMO = −2.922 eV (doped ZnO). The results can not only provide an important indication about the influence of Co and rGO on the activity of CO2 photoreduction over ZnO but also demonstrate a strategy for tuning the CO2 photoreduction performance. Our work may lay the groundwork for directing the future design of efficient metal-modified ZnO photocatalysts for CO2 reduction.
Published: 1 June 2021
Materials Today Chemistry, Volume 20; doi:10.1016/j.mtchem.2021.100427

Abstract:
Perovskite solar cells (PSCs) are rapidly approaching as promising processes toward efficient energy harvesting technologies. High cost and low environmentally stable organic hole transporting materials (HTMs) are the main hurdles in their commercial realization. Perovskite community is actively looking for inorganic HTMs which will potentially yield into a pragmatic solution. Cu-based materials, e.g. Cu-based oxides, halides, and chalcogenides exhibit features like low production cost, suitable band alignment, and high hole mobility Due to these properties, Cu-based materials are being explored as potential HTMs in PSCs. Significant efforts are contributed toward using low-cost Cu-based materials because of high chemical stability, high carrier mobility, low-cost and the possibility of developing a very simple technique. The photo-physical properties, e.g. optical electronic structure, valence band engineering, and carrier mobility are briefly discussed. Detailed insights toward understanding the development of Cu-based HTMs along with their possible pragmatic commercialization aspects are presented. This article highlights the utilization of Cu-based chalcogenide HTM and role of ternary Cu-based chalcopyrite, Pnma ternary chalcogenides, sulvanite and oxychalcogenides in the field of PSC with a brief idea about tailoring their optoelectronic properties. This article will significantly help the community toward the engineering of novel Cu-based HTMs for possible commercialization of PSC technology.
Zongjie Zhang, Balaji Devakumar, Shaoying Wang, Liangling Sun, Nan Ma, Wei Li,
Published: 1 June 2021
Materials Today Chemistry, Volume 20; doi:10.1016/j.mtchem.2021.100471

Abstract:
White light-emitting diodes (LEDs) with high color rendering index (CRI) and low correlated color temperature (CCT) are desirable for next-generation solid-state lighting. In this work, we demonstrated an efficient near-UV-excited cyan-emitting phosphor based on Ce3+-doped Ca2LuHf2Al3O12 (CLHAO) garnet, which could be used to cover the cyan gap for fabricating high-CRI warm-white LEDs. We found that the CLHAO:Ce3+ samples exhibited a broad excitation band in the 300–450 nm wavelength range peaking at 400 nm, and upon 400 nm excitation they showed broad cyan emission bands in the 420–600 nm spectral region with peak positions ranging from 477 to 493 nm. The optimal CLHAO:0.02Ce3+ sample had CIE color coordinates of (0.160, 0.255), and its internal and external quantum efficiencies were measured to be 84.3% and 60.8%, respectively. Impressively, the luminescence intensity of CLHAO:0.02Ce3+ sample at 423 K still remained at 62% of the initial value at 303 K, and the chromaticity shift was calculated to be as low as 1.7 × 10−2, revealing its high thermal stability and color stability at a higher temperature. Finally, a warm-white LED device (CCT = 3,194 K) was fabricated by combining CLHAO:0.02Ce3+ cyan phosphors with commercial blue/green/red tricolor phosphors, showing bright white-light emission with a high CRI of 89.4, which was superior to that of another warm-white LED device (CRI = 83.2) fabricated without CLHAO:0.02Ce3+ cyan phosphors. These outstanding luminescence properties of CLHAO:Ce3+ cyan phosphors illustrated that they offer a new feasible approach for the production of high-CRI warm-white LEDs toward high-color-quality solid-state lighting.
L. Huang, Z. Luo, , Q. Zhang, ,
Published: 1 June 2021
Materials Today Chemistry, Volume 20; doi:10.1016/j.mtchem.2021.100475

Abstract:
Covalent triazine frameworks (CTFs) have recently attracted increasing attention in various fields. However, it is still challenging to prepare CTFs with good crystallinity via an efficient approach under mild conditions. This work offered a useful protocol based on a homogeneous solvothermal monomer/catalyst/solvent system for the preparation of crystalline CTFs, directly from several nitrile-containing monomers. The synthesized CTFs were featured with good crystallinity and high thermal stability. Finally, an afforded CTF material was applied as a photocatalyst for the degradation of Rhodamine B with excellent performance. Meanwhile, the CTF material was found to be chemically stable after the photocatalytic reaction.
K. Gao, X. Guo, , J. Wang, L. Wang
Published: 1 June 2021
Materials Today Chemistry, Volume 20; doi:10.1016/j.mtchem.2021.100458

Abstract:
Polymers with excellent comprehensive performance toward enhanced stability and mechanical strength are attractive for matrix loading of tunable porous and inherently brittle metal−organic frameworks (MOFs). Polyethersulfone (PES) with high mechanical strength (elastic modulus = ~2.6 GPa) is one of the best polymeric materials widely applied in gas and liquid separations but hindered by its ability to adhere to MOFs surface. The combination of the interface width, porosity, atomic density, and hydrogen bonding number and strength strongly influences MOFs/PES compatibility. ZIF-8 is one of the most frequently investigated MOFs, and exhibits excellent interface compatibility with PES, which is confirmed by both computational and experimental analyses. The desired porosity and adsorption properties of ZIF-8 are retained in ZIF-8/PES composites. This study sheds light on the theoretical understanding and characterization of hybrid material systems with diverse differences between brittle MOFs and stiff polymers.
Y. Roina, F. Auber, ,
Published: 1 June 2021
Materials Today Chemistry, Volume 20; doi:10.1016/j.mtchem.2020.100412

Abstract:
Polytetrafluoroethylene (PTFE) is a ubiquitous material used in implants and medical devices in general due to its high biocompatibility and inertness; blood vessels, heart, jawbone, nose, eyes, or abdominal wall can benefit from its properties in the case of disease or injury. Its expanded version, ePTFE, is an improved version of PTFE with better mechanical properties, which extend its medical applications. However, ePTFE implants often lack improvement in properties such as antibacterial, antistenosis, or tissue integration properties. Improvements in these properties by several strategies of functionalization for medical purposes are discussed in this review. Covalent and non-covalent bonding are reviewed, including more specifically chemical impregnation, chemical surface modification, autologous vascularization, and cell seeding, which are strategies mainly used for improving the properties of ePTFE and are described in this review.
, P.R.L. Dabare, , A. Postma,
Published: 1 June 2021
Materials Today Chemistry, Volume 20; doi:10.1016/j.mtchem.2021.100444

Abstract:
A well-defined AB diblock copolymer of 2-vinyl-4,4-dimethylazlactone (VDA) and N,N-dimethylacrylamide (DMA) was generated by reversible addition-fragmentation chain transfer (RAFT) radical polymerization. The VDA-DMA diblock copolymer was reacted with 2-(methylthio)ethylamine (MTEA) and 3-(methylthio)propylamine (MTPA) to yield two novel thioether functional diblock copolymers whose structure was confirmed using 1H NMR and FTIR spectroscopy. Both diblock copolymers formed micelles (20–30 nm) in aqueous media as confirmed by dynamic light scattering (DLS) and transmission electron microscopy. The self-assembled micelles were loaded with Nile Red, a model hydrophobic drug to study their ROS-triggered release mechanism. On addition of hydrogen peroxide (H2O2), the most common ROS species, the hydrophobic thioether core of these micelles oxidized, and both diblock copolymers became more hydrophilic. This triggered their disassembly and subsequent cargo release as characterized by UV–visible spectroscopy. The Nile Red loaded micelles demonstrated similar in-vitro ROS-mediated release when exposed to endogenous oxidants in a model inflammation environment simulated by the presence of activated macrophages. The responsive nanomaterials developed in this article have promising potential as drug carriers in applications where ROS-triggered delivery of cargo is required such as in inflammatory conditions.
D.S. Monje, K.M. Chacon, I.C. Galindo, C. Castaño, L.M. Ballesteros-Rueda, G.C. Valencia, M.C. Gonzalez,
Published: 1 June 2021
Materials Today Chemistry, Volume 20; doi:10.1016/j.mtchem.2021.100445

Abstract:
Carbon dots have been synthesized through a pyrolysis route with agroindustrial wastes of Yerba Mate (YM), Avocado Seed (AS), and Orange Peel (OP) as raw materials. The selection of the pyrolysis temperature was according to the thermogravimetric profile of the raw materials. A thorough characterization by transmission electron microscopy (TEM), ζ-potential, ultraviolet visible spectroscopy (UV/vis), Raman, Fourier transform infrared (FTIR) spectroscopy, and steady-state, and time-resolved area normalized emission spectroscopy (TRANES) suggest spherical nanomaterials with diameters lower than 5.0 nm and polyfunctional surfaces with an abundance of negatively charged surface groups. Regarding their application as photocatalyst and as Pickering emulsion stabilizers, all materials have different performances. In the first case, almost 100% and 40% of the photodecoloration of methylene blue was achieved in 2 h by the materials obtained from YM and AS, respectively. Nevertheless, different mechanisms were proposed for both cases. Regarding their performance as Pickering emulsion stabilizers, all materials show different performances. Interestingly, Raman spectroscopy results provide useful information to understand the observed results.
Manav R. Kar, Mihir R. Sahoo, ,
Published: 1 June 2021
Materials Today Chemistry, Volume 20; doi:10.1016/j.mtchem.2021.100449

Abstract:
In the past few years, Pb-free metal halide perovskites have been recognized as a promising material for various optoelectronic applications because of some of their unique features, such as direct and tunable bandgap, visible light emission, narrow emission spectra, lower toxicity level, and easy solution processability. Recently, several Bi-based perovskite-like single crystals (SCs) and nanocrystals (NCs) were reported, which are mostly suffering from their poor structural stability and lower emission intensity. Here, we report the growth of millimeter-sized formamidinium bismuth bromide (FA3Bi2Br9) perovskite SCs via slow solvent evaporation method. They crystallized into a trigonal crystal structure and exhibit an indirect bandgap of 2.71 eV. These results are supported by the first-principle density-functional theory studies. We have also synthesized nanometer-sized spherical blue-emitting FA3Bi2Br9 NCs by solvent ligand-assisted reprecipitation method and achieved a maximum photoluminescence quantum yield of 22%. We observe that the addition of excess ligands into the FA3Bi2Br9 NCs solution before the purification step significantly improves the optical and colloidal stability of the NCs.
, R. Gupta, G. Sharma, K. Vemula, A.R. Koirala, , E.H. Choi, D.Y. Kim, L.P. Purohit, B.P. Singh
Published: 1 June 2021
Materials Today Chemistry, Volume 20; doi:10.1016/j.mtchem.2021.100452

Abstract:
We synthesized yttrium-doped CNT-ZnO (CNT-YZO) nanoparticles (NPs) and nanoflowers (NFs) from the hydrothermal method at 130 °C. The effect of Y3+-concentrations in nanostructured CNT-YZO was determined in terms of the photocatalytic degradation of methylene blue (MB). Microstructural analysis showed the hexagonal cubic structure of ZnO regardless of Y-concentration or the addition of CNTs during the nucleation and growth. The specific surface area, total pore volume, and mean pore diameter of typical CNT-YZO NFs were observed to be 36.109 m2/g, 0.162 cm3/g, and 17.932 nm, respectively. The photocatalytic degradation performance of CNT-YZO NFs improved due to increase reactive sites of the catalyst and reduced recombination of photo-induced carriers. The surface-area normalized first-order decomposition rates (r/m2) of CNT-YZO NFs showed the highest photocatalytic degradation (99%). The CNT-YZO has produced a new kind of material for the photocatalytic degradation under the irradiation of visible light using a solar simulator.
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