查看更多>>摘要：A new boron-rich boride carbide of sodium, NaB13C2 single crystals have been successfully synthesized from the elements under high temperature and high pressure. The crystals are reddish black with a metallic luster and show a regular hexagonal prism shape. NaB13C2 crystallizes into an orthorhombic LiB13C2-type structure with a space group of Imma (No. 74) and the lattice constants are a = 10.9417 A, b = 5.6756 A, c = 8.0898 A. The crystal structure is characterized by a covalent framework of B12 icosahedra connected by CBC chains and Na atoms located in the void of the framework. The measured and calculated Raman spectra of NaB13C2 are in good agreement and show expected oscillations of the covalent framework. The electronic band structures reveal that NaB13C2 is a wide band gap semiconductor with a band gap of 3.36 eV. As a novel wide band gap semiconductor, NaB13C2 may have potential applications in semiconductor field. (c) 2021 Elsevier B.V. All rights reserved.
Moghadas, Bahareh KamyabTamjidi, SajadAfrooz, Mohammad Reza
16页
查看更多>>摘要：Pollutant risen by metal ions in industrial effluent is the main environmental challenges of human life. Notwithstanding the universal economic crisis providing cost-effective and efficient methods to remove pollutants is an essential need of human society. The adsorption method is extensively utilized owing to its mutability to design, reversibility, low cost, and effective and desirable results; therefore, the need to achieve environmentally friendly and cost-effective adsorbents to remove these metals is more than ever. Most recently, the use of microorganisms as inexpensive sorbents has avowed consideration that among them bacteria, due to their unique features such as their certain compounds in the cell wall, Peptidoglycan, and the influence of FGs, carboxyl, amines, and phosphonates, has led to the excellent biosorption potential for bacteria. In addition to examining different methods of removing heavy metals, this study addresses the utilization of bacteria as bio-sorbents for metals uptake, the dangers, and the origin of heavy metals. Furthermore, bacterial biomass's thermodynamic, isotherm, and kinetic demeanors of the heavy metal ion biosorption method have been investigated. (c) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Gas sensors fabricated by metal oxide semiconductors (SMOs) exhibited promising prospect for acetone detection due to their high sensitivity, small sizes, simple operation, facile fabrication and low cost. However, the current SMOs still face diverse challenges involving high power consumption, low response, poor anti-interfering ability and weak repeatability. In this work, in order to meet the ever-increasing requirements for acetone detection, Pt nanoparticles (NPs) were embedded into ZIF-8 templates then loaded on porous SnO2 nanofibers (NFs) via electrospinning and subsequent annealing process with a control of heating rate. The gas sensing characteristics of pristine SnO2, SnO2-ZnO, and Pt-ZnO-SnO2 porous NFs were investigated. The Pt-ZnO-SnO2 porous NFs displayed an ultrahigh response (R-a/R-g = 104.26-100 ppm at 170 degrees C), high selectivity and low detection limit (200 ppb) to acetone during dynamic measurements. In this study, the advanced sensing behavior can be ascribed to the multi-heterojunctions construction at the interface of SnO2-ZnO, ZnO/PtO2 and SnO2/PtO2, the increasement of oxygen vacancies, as well as the electronic and chemical sensitization of Pt NPs. The well-dispersed and ultrasmall-sized Pt NPs (similar to 3 nm) functionalized on porous SnO2 NFs also play an essential role in fabricating high-performance acetone sensors. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Two kinds of ligand-free upconversion nanoparticles (UCNPs) that exhibit green emission and red emission respectively were successfully synthesized for the study of reactive oxygen species (ROS) generation in photodynamic therapy (PDT). Fourier-transform infrared spectroscopy (FT-IR) confirmed the removal of oleate ligand from the surface of UCNPs after acid treatment. X-ray diffraction (XRD) and transmission electron microscope (TEM) analysis revealed that both oleate-capped and ligand-free UCNPs had the tetragonal phase and the single-crystal structure. The particle sizes analyzed by dynamic light scattering (DLS) were in line with the data from TEM. The photoluminescence (PL) spectra showed that the removal of the oleate ligand had no notable effect on the fluorescence intensities of both UCNPs. Two photosensitizers (PSs), merocyanine 540 (MC 540) and chlorin e6 (Ce6), were used as the energy acceptors and coupled with the energy donors (UCNPs) for luminescence resonance energy transfer (LRET) and ROS generation studies. By comparing the quenching efficiencies of PL spectra of the oleate-capped and ligand-free Ho3+-doped UCNPs/MC 540 pairs with those of Er3+-doped UCNPs/Ce6 pairs, it was found that the quenching efficiencies caused by the adsorption of MC 540 on the surface of both types of Ho3+-doped UCNPs were greater than those of Er3+-doped UCNPs/Ce6 pairs. Subsequently, the investigation of the generation of ROS was performed by using 9,10-anthracenediyl-bis(methylene) dimalonic acid (ABDA) to detect the production of reactive oxygen species. The results showed that among the four combinations of LRET pairs, the ligand-free Ho3+-doped UCNPs/MC 540 pair exhibited more pronounced ROS generation due to the occurrence of more effective LRET between the UCNP donor and the MC 540 acceptor. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：The heterogeneous Bi2O2SiO3-Si2Bi24O40 (BOS-BSO) photocatalyst has been prepared in situ by an en-vironmentally friendly hydrothermal deposition. By controlling the molar concentration of the bismuth source and the silicon source (nBi:nSi) in the precursor, optimizing the heat treatment process parameters and adjusting the reaction time and temperature, the phase composition and crystallinity can be adjusted and the effective heterojunction and heterogeneity can be obtained. At the same time, the hydrothermal process forms a special 3D cross-linked sheet-like structure of bismuth silicate, which can provide graded adsorption channels for pollutants. In the BOS-600(treated at 600 degrees C) photocatalyst, the photocatalytic performance is 3 times and 29 times than that of BOS and P25, respectively, and excellent catalytic stability is observed even after three test cycles. Compared with the BOS powders, BOS-600 has moremiddotOH radicals and produces center dot O-2(-) on the surface which play an important role in the degradation of RhB due to the up-shift structure (Vo level). The formation of the Bi2O2SiO3-Si2Bi24O40 heterojunction in BOS-600 and the presence of oxygen vacancies caused by the highly active surface produce a synergistic effect, which significantly improve the carrier separation efficiency and increases the redox capacity of the sample. (C) 2021 Published by Elsevier B.V.
查看更多>>摘要：To maintain the substrate strength and toughness of WC-Co cemented carbide as well as improve its adhesion with a diamond coating deposited by hot filament chemical vapor deposition (HFCVD), a novel conversion annealing pretreatment was studied. The pretreated substrates, as-nucleated, and as-grown diamond coating specimens were characterized using X-ray diffraction, scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and Rockwell hardness tests. It was found that conversion treatment could effectively convert the Co in the surface layer into intermetallic (Co3W, Co7W) and/or Co-rich compound (M6C, M12C) phases. The conversion layer underwent a re-carburization process during the nucleation stage of HFCVD. The intermetallic phases returned to the gamma-Co (W) phase which will be encapsulated by the freshly formed WC layer. This is beneficial for seeding growth and new diamond nuclei formation. However, those Co-rich carbides consumed much carbon atoms to decompose and react to form a lot of free gamma-Co phase during the nucleation stage, which promoted severe graphitization at the growth interface during HFCVD, and caused the film to peel off. A high-quality microscale diamond coating with an adhesion of the HF 2-3 level could be deposited onto the conversion layer with only the WC and Co3W phases. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Lead halide perovskites possess excellent photoelectric properties and are promising for photocatalysis. However, the toxicity of lead in these perovskites has hindered their application. We designed a stable, lead-free heterojunction to enhance the photocatalytic efficiency of the perovskite. A production rate of 1465 mu mol/g/h for the selective oxidation of benzyl alcohol was achieved, which was the highest among all inorganic catalysts without zero-valent metal cocatalyst in the atmosphere at room temperature. In addition, the heterojunction degraded 74.7% of 10 ppm 2-mercaptobenzothiazole within 10 min, and achieving a final degradation rate exceeding 99.9% in 20 min, which is the best degradation efficiency among all reported studies. Detailed optical characterisation proved that the high efficiency stems from band matching and charge transfer between Cs3Bi2Br9 and TiO2. This result will inspire the design of additional lead-free perovskites for photocatalysis. (C) 2021 Published by Elsevier B.V.
查看更多>>摘要：The practical utilization of lithium-sulfur (Li-S) batteries is obstructed by the shuttle effect and sluggish conversion kinetics of the lithium polysulfides (LiPS). Herein, cobalt nanoparticles embedded N-doped carbon composite (Co-NC) decorated metallic tin with three-dimensionally ordered macroporous (3DOM) structure is designed to deal with these issues. The ordered interconnected macropores of the unique hierarchical structure can provide smooth Li ion transport, and the micro-/mesopores of Co-NC derived from ZIF-67 can trap polysulfides. Additionally, the highly conductive metal Sn as 3DOM skeleton accel-erates charge transfer and strengthens the LiPS adsorption. Meanwhile, the embedded Co-NC further facilitates the polar adsorption of LiPS as well as its conversion kinetics. Benefiting from these features, the Co-NC@Sn (NH3) composite shows a relatively low capacity fading rate of 0.045 % per cycle over 500 cycles at 1 C. Even with raised sulfur loading of 5.2 mg cm(-2), a high areal capacity of 4.65 mAh cm(-2) can be obtained. Pouch cell fabricated with Co-NC@Sn (NH3) delivers a high discharge capacity of 701 mAh g(-1) under high sulfur loading of 4.50 mg cm(-2), implying the superiority of the S/Co-NC@Sn (NH3) cathode. This work provides a new strategy in efficient sulfur immobilizer design for advanced Li-S batteries development. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：CoSe2 has been as one of promising electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) due to its earth-abundant resource, and tunable electronic structure. However, enhancing electrocatalytic activity of CoSe2 to meet the large-scale practical applications is desirable. Herein, we report a facile plasma nitridation strategy to generate N-doped CoSe2 nanomesh arrays on commercial carbon paper (N-CoSe2@CP). The obtained N-CoSe2@CP electrodes combined advantages of abundant electrochemical active sites and beneficial electronic structures, thus exhibiting a low over-potential of 106 mV and 237 mV to drive 10 mA cm(-2) towards HER and OER in alkaline medium, respec-tively. Moreover, it can be employed as bifunctional electrocatalyst for overall water splitting, where a small potential of 1.57 V was required to reach 10 mA cm(-2), and long-term stability was also realized. This work develops a promising strategy to explore highly-efficient nanocatalysts towards new energy conversion. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Organic-inorganic perovskites such as iodine methylamine lead (MAPbI(3)) shows superb photocatalytic prospect in the field of solar energy driven photocatalysis. However, its catalytic performance is insufficient due to serious charge recombination. In this article, 1T-2H MoSe2/MAPbI(3) composites were obtained by simple electrostatic adsorption method. The results of photocatalytic hydrogen production showed that 10 wt% 1T-2H MoSe2/MAPbI(3) performed the best hydrogen evolution rate of 552.93 mu mol.h(-1).g(-1), which was 23 times than that of pure MAPbI(3) (23.13 mu mol.h(-1).g(-1)). The long-term cyclic stability test also indicated that 1T-2H MoSe2/MAPbI(3) composites have good stability. The excellent hydrogen evolution rate activity is thoroughly investigated by optical/optoelectrochemical measurements, showing that 1T-2H MoSe2 as a cocatalyst can effectively transfer electrons and promote the separation of photogenerated charge. This study provided a reference for further exploration of MAPbI(3)-based catalysts with excellent catalytic activity. (C) 2021 Elsevier B.V. All rights reserved.
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