查看更多>>摘要：? 2022 Elsevier B.V.The construction of a Z-scheme heterojunction favors the improvement of the photocatalytic activity of photocatalysts. Herein, the LaVO4/Bi3O4Cl Z-scheme heterojunction was designed reasonably by the method of in situ growth. The obtained heterojunction was further used as a photocatalyst for the degradation of ofloxacin (OFX), an antibiotic, in wastewater. The degradation efficiency of OFX by the optimal sample (LBC-2) was 94.3 % and the values of k were about 114.7 and 2.4 times those of LaVO4 and Bi3O4Cl, respectively. In addition, LBC-2 maintained high activity after 4 cycles. The significantly reduced recombination rate of carriers in LBC-2 was reflected by the results of the photoluminescence (PL), photocurrent (PC), and electrochemical impedance spectroscopy (EIS) studies. The degradation pathways of OFX were proposed accounting to the intermediates detected by liquid chromatography-mass spectroscopy (LC-MS). Toxicity estimations showed that the toxicity of some intermediates decreased. This work provides new insight into the development of Z-scheme photocatalysts for the removal of antibiotics as pollutants.
查看更多>>摘要：? 2022 Elsevier B.V.A novel thermomechanical processing including solution treatment, first rolling with large deformation and overaging based on particle-stimulated nucleation of recrystallization (PSN) was proposed to obtain an Al–Mg–Si alloy sheet with fine grain structure, weak texture and high plastic strain ratio. The difference between conventional thermomechanical processing and novel thermomechanical processing with two overaging time parameters was investigated by texture and microstructure characterization and tensile tests. The results show that the finest grain structure with an average size of 17 μm, the weakest recrystallization texture with a volume fraction of 8.4 %, the highest average plastic strain ratio r of 0.69 and the lowest planar anisotropy Δr of ? 0.001 were acquired by the novel thermomechanical processing with a long overaging time. In comparison with conventional thermomechanical processing, the novel thermomechanical processing can generate completely different particle distributions and tends to develop a weak texture consisting of the CubeND {001}<310>orientation. Increasing the overaging time is effective in coarsening the particles and thus refining the grain structure, weakening the texture, and improving the average r and Δr values. The genetic characteristics of texture evolution and the particle distribution determine the final recrystallization texture.
查看更多>>摘要：? 2022 Elsevier B.V.In this work, typical refractory pollutant Rhodamine B (RhB) was effectively degraded by Cu-Fe LDHs/Bi2WO6 composite in the photo-Fenton process. The hydrothermal synthesis of Cu-Fe LDHs/Bi2WO6 composite with ethylene glycol as reductant created the multivalent coexistence of the same metal element to achieve a self-circle redox reaction between metals. The photo-Fenton process by Cu-Fe LDHs/Bi2WO6 incredibly eliminated the limitation of strong acidic pH value applied in the Fenton process. ?OH generated by Cu-Fe LDHs/Bi2WO6 was 5 times that of Cu-Fe LDHs during the photo-Fenton process. The complete degradation of RhB in the photo-Fenton process under the optimal conditions of initial pH= 6, 5 mmol/L of H2O2, and 1 g/L of Cu-Fe LDHs/Bi2WO6 dosage was far more than 46% of RhB degradation in the photocatalytic process and 76% of RhB degradation in the Fenton process. Cu-Fe LDHs/Bi2WO6 composite exhibited the excellent redox ability, electron transfer ability and reusability during the photo-Fenton process. The acceleration of Fe3+/Fe2+ cycles in the Cu-Fe LDHs/Bi2WO6/H2O2/Vis system was mainly ascribable to the combination of efficient transfer of photogenerated electrons and self-circle redox of Fe3+/Cu+. It is expected for the promising application of multivalent bimetallic photo-Fenton catalysts and rendering enlightenments for photo-Fenton catalytic oxidation reaction.
查看更多>>摘要：? 2022 Elsevier B.V.The microstructural evolution and its consequence on the room and elevated temperature (500 °C) tensile properties of the Ti-6Al-2Sn-4Zr-2Mo-0.1Si (Ti6242S) alloy fabricated via the laser powder bed fusion were investigated after the following heat treatments: solution treatment followed by aging (STA), super-transus heat treatment, and water quenching (WQ) after annealing at a sub-transus temperature (885, 925, 954, and 982 °C) in the (α + β) regime. The super-transus heat treatment results in the removal of columnar prior β grains and formation of equiaxed grains that consist of α colonies. The WQ triggers the formation of a bimodal microstructure of α and α′ phases, and the volume fraction of α′ phase increases with increasing the WQ temperature. The STA process leads to a high yield strength (σy: ~658 MPa) and an elongation to fracture (εf: ~14.8%) when tested at 500 °C. The super-transus heat treatment results in a lower yield strength at both room and elevated temperatures due to coarsening of the α laths. The WQ process allows for the tailoring of the tensile property in a broad window, and the yield strength increased with increasing WQ temperatures. Particularly, the 885 and 925-WQ samples showed a remarkably enhanced strain hardening behavior during tensile tests. The 925-WQ samples exhibited a high σy of ~706 MPa and an εf of ~11.0% at elevated temperature. The samples that underwent STA processing and 925-WQ showed a higher σy while maintaining a decent ductility relative to the conventionally fabricated counterparts at 500 °C, indicating the potential elevated temperature applications for the Ti6242S alloy fabricated via laser powder bed fusion coupled with heat treatment.
查看更多>>摘要：? 2022 Elsevier B.V.Facile deposition of ternary semiconducting Cu2ZnSnS4 (CZTS) thin films has been a challenge due to a very narrow range of single phase stability in the Cu-Zn-Sn-S system. While sputtering has been a very efficient method of growth of various optoelectronic thin films, the formation of secondary phases should be suppressed during sputter deposition of CZTS films. Differently with the reported studies on deposition of a precursor film followed by a delicately - controlled sulfurization process required for the formation of the kesterite CZTS phase, we demonstrate a single step synthesis route to grow phase pure CZTS thin films using a single elementary target with excess Cu by RF magnetron sputtering at a substrate temperature of 450 °C. The route did not require any post-deposition sulfurization. These films had an optical band gap of ~1.6 eV and white light sensitivity> 200% at a bias potential of 5 V, highly suitable for photovoltaic and photocatalytic activities. Detailed electro-impedance analyses from Nyquist, Bode and Mott-Schottky plots of a Mo/CZTS/Pt/electrolyte device revealed p-type conductivity with a flat band potential of 0.51 V (reversible hydrogen electrode), carrier concentration of 6.2 × 1017 cm?3 and a carrier life time as high as of ~17 μs.
查看更多>>摘要：? 2022Developing a simple oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) bifunctional catalyst construction strategy for zinc-air batteries (ZABs) has been a major challenge. Therefore, this study synthesized an ultrathin nitrogen-doped defective carbon layer embedded with nickel-iron (NiFe) (ZGNiFe@NG) by introducing zinc gluconate to the precursor. In situ generated NiFe nanoparticles facilitated the OER catalyzation kinetics process, nitrogen-doped graphene demonstrated a large specific surface area, providing more active sites to boost electron transfer and mechanical support for the NiFe nanoparticles. Additionally, the introduction of Zn ions can enrich carbon vacancies in the structure of composite catalyst, which is beneficial to the further improvement of catalytic activity. The investigations revealed that the obtained ZGNiFe@NG catalyst possessed a higher ORR half-wave potential of 0.81 V and a lower OER potential of 1.65 V of 10 mA cm?2, presenting a bifunctional catalytic activity toward ORR and OER than that of catalysts lacking the Zn ion precursor. Moreover, as expected, the fabricated solid-state flexible ZAB with ZGNiFe@NG catalyst delivered a high power density of 84.95 mW cm?2 at a current density of 112 mA cm?2 and could operate 65 h steadily. In summary, this work paves a way for designing a carbon matrix with dopants and defects to load NiFe nanoparticles as superior cathode materials of ZABs.
查看更多>>摘要：? 2022 Elsevier B.V.A ratiometric electrochemical sensor is developed for fast, simple and accurate determination of BHA using polythionine/multiwalled carbon nanotube composite modified glassy carbon electrode (pThi/MWCNT/GCE). The preparation of pThi/MWCNT/GCE is characterized by various analytical techniques. The pThi/MWCNT composite is demonstrated to possess large specific surface area, good electrical conductivity, and high electrocatalytic ability. Moreover, it is demonstrated that the use of ratiometric signal involving the electro-oxidation of both BHA and pThi improves the accuracy and reliability of the BHA analysis due to the built-in correction function of the inner reference polythionine probe. A linear ratiometric signal can be achieved over the concentration range of 0.5–70.0 μM with the detection limit of 0.21 μM (S/N = 3). The BHA sensor also exhibits high selectivity, high reproducibility, and good stability, and can be used for the analysis of BHA in edible oil samples with satisfactory results.
查看更多>>摘要：? 2022 Elsevier B.V.MgFe2O4/SrTiO3 and MgFe2O4/SiO2 nanocomposites were prepared via a modified sol-gel auto combustion method. X-ray diffraction (XRD) patterns confirmed the formation of both MgFe2O4/SrTiO3 and MgFe2O4/SiO2 nanocomposite structures. Williamson-Hall analyses showed that MgFe2O4/SrTiO3 had a crystallite size of 18 nm, while it was 17 nm for MgFe2O4/SiO2. It was found that the lattice constant for MgFe2O4/SiO2 was longer than that for MgFe2O4/SrTiO3; thus, the cell volume was larger for MgFe2O4/SiO2 nanocomposite. Fourier transform infrared (FTIR) spectra for MgFe2O4/SrTiO3 and MgFe2O4/SiO2 nanocomposites revealed absorption bands corresponding to bending vibrations of the TiO6 octahedron and Si―O―Si with symmetric and antisymmetric stretching vibrations. The electrochemical characteristics showed that MgFe2O4/SrTiO3 and MgFe2O4/SiO2 nanocomposites exhibited similar initial discharge capacity values, while MgFe2O4/SrTiO3 had a higher coulombic efficiency of 64.1%. After 100 cycles, MgFe2O4/SrTiO3 delivered a discharge capacity of 311 mAh g?1, larger than MgFe2O4/SiO2. Furthermore, MgFe2O4/SrTiO3 nanocomposite demonstrated significantly improved high rate capability, with a capacity of 330 mAh g?1 and 65% retention of the 2nd cycle, compared to MgFe2O4/SiO2 (with a capacity of 252 mAh g?1 and 42% retention of the 2nd cycle) after the current density was returned to 100 mA g?1.
查看更多>>摘要：? 2022 Elsevier B.V.Hydrogen production by electrocatalytic water splitting is one of the most promising ways to solve energy crisis and environmental pollution. In this work, we investigated the effect of Ce element on the catalytic activity of water oxidation and urea oxidation. Taking the N-Ni3S2 as an example, the N-Ce-Ni3S2 and N-Ni3S2 @Ce(OH)3 were firstly synthesized by doping Ce element into N-Ni3S2 and constructing the interface of N-Ni3S2 and Ce(OH)3. This N-Ni3S2 @Ce(OH)3 exhibits enhanced catalytic activity through the construction of heterogeneous interfaces, whether water oxidation (overpotential of 360 mV @ 50 mA cm?2) or urea oxidation (1.37 V @ 100 mA cm?2). A series of experiments show that the construction of heterogeneous interface greatly enhances the electron transfer rate of the N-Ni3S2 @Ce(OH)3 material, promotes the exposure of more active sites and improves the conductivity of the material. The density functional theory calculation also provides the water adsorption energy of the N-Ni3S2, N-Ce-Ni3S2 and N-Ni3S2 @Ce(OH)3 materials, and it is found that the N-Ni3S2 @Ce(OH)3 materials give optimal water adsorption energy compared with the N-Ni3S2 intrinsic materials. Experimental results and theoretical calculations show that the main reasons for the increase in activity are exposure of more active sites and higher electron transfer rate rather than stronger water adsorption energy.
查看更多>>摘要：? 2022 Elsevier B.V.Ethanol, as one of the common volatile organic compounds (VOCs), has serious harm to the human central nervous system. The high-efficiency detection of ethanol gas at room temperature (RT) has attracted widespread attention in the field of current gas-sensing detection. Here, we designed and prepared ternary nanocomposites constructed with two-dimensional MXene and MoO2/MoO3 nanosheets, which can be used in the field of low-concentration ethanol detection at RT. The MoO2/MoO3/MXene nanocomposites make full use of the excellent electrical conductivity and large specific surface area of MXene, which provides more active adsorption sites and reaction centers. Moreover, the construction of n-n heterojunctions between uniformly grown MoO2 and MoO3 nanosheets significantly enhances the response of the sensor. The gas sensing results revealed that MoO2/MoO3/MXene nanocomposites showed high response (Ra/Rg = 19.77 @200 ppm) to ethanol at RT, with a detection limit of 5 ppm (Ra/Rg = 2.07). At the same time, the sensor also has excellent selectivity and fast response-recovery to ethanol (46 s/276 s). Further, the possible gas sensing mechanism of the composites was proposed and discussed. This work suggests the promising applications of metal oxides heterojunctions/2D hybrid materials for VOCs gas sensing detection at RT.
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