查看更多>>摘要：? 2022 Elsevier B.V.In this work, N-doped hierarchically porous carbon (PDHC) has been prepared when MnO2 nanotube and polyaniline are selected as self-sacrificial reaction template and carbon source, respectively. Benefiting from the suitable N-doping degree inherited from polyaniline, and the hierarchical porous structure originated from the synergistic adjustment of self-sacrificial template and activation treatment, PDHC exhibits significant advantages for electrochemical energy storage. Typically, the PDHC has the high specific capacitance (467 F g?1 at 1 A g?1) and rate performance (71.9% capacitance retention at 20 A g?1) in three-electrode systems. PDHC-based coin type symmetric supercapacitors are assembled with 1 M H2SO4 electrolytes and ionic liquid electrolytes, respectively, and they all exhibit a considerable synergistic power-energy output (752 W kg?1 at 31.1 Wh kg?1 and 750 W kg?1 at 74.8 Wh kg?1) and an acceptable cycling stability (6.5% and 13.9% loss over 5000 cycles). Meanwhile, the electrocatalytic performance of PDHC towards oxygen reduction reaction is also investigated, where a superior catalytic activity and a outstanding durability via 4e- pathway in the alkaline solution are confirmed, heralding the possibility of its practical application in fuel cells.
查看更多>>摘要：? 2022 Elsevier B.V.To improve the inherently low electrical conductivity of Na3V2(PO4)2F3, we design a three-dimensional conductive network and prepare it by hydrothermal strategy. Gelatin can reduce impurities and make the material shape more regular while graphene acts as conductive network that can improve the electrochemical properties. The prepared NVPF-gel/rGO shows a superior sodium storage performance. The reversible capacity is 125.1 mAh g-1 at 0.2 C, 108 mAh g-1 after 200 cycles, and 90.6 mAh g-1 at 5 C. Furthermore, the full cell is successfully fabricated using the hard carbon anode (average working voltage of 3.3 V). NVPF-gel/rGO composite is a potential sodium storage cathode with a good practical application prospect.
查看更多>>摘要：? 2022 Elsevier B.V.The extensive application of silicon (Si) anodes is still impeded, although Si has long been considered as the most potential anode material for the high-energy lithium-ion batteries. In the composition of anodes, binders with a small proportion contribute no direct capacity to the cell, but play a vital role in addressing the issues associated with Si materials (e.g., huge volume expansion, unstable solid electrolyte interphase (SEI) layer and low electrical conductivity). Herein, we design a moderately cross-linked polymer binder polyacrylic acid (PAA)–sodium alginate (SA) to balance the degree of crosslinking and the number of free groups within this polymer structure via a simple esterification reaction, which can support micro-sized silicon dendrites (SD) to form a three-dimensional (3D) anode. The PAA-SA binder with a moderately cross-linked structure can simultaneously realize the mechanical strength, chemical stability, and polymer viscosity, resulting the Si anodes with restricted volume expansion and stable SEI layers during long cycles. Therefore, the SD/PAA-SA anode exhibited superior cycling performance (2929.8 mA h g?1 for 1st cycle, initial Coulombic efficiency of 80.1 % and 1419.8 mA h g?1 at 1 A g?1 after 200th cycle) and good mechanical properties. This work designs a water-soluble binder with a moderately cross-linked polymer structure, which can be applied to developing electrodes with compatible sustainability and electrochemical activity.
查看更多>>摘要：? 2022 Elsevier B.V.In this work, AgInS2 (AIS) and cobalt (Co) doped AgInS2 (Co-AIS) are prepared by low-temperature liquid phase method using thioglycolic acid (TGA) as the stabilizing agent. The crystal structure, surface elements, binding energy, particle morphology, and optical properties of AIS and Co-AIS are analyzed by XRD, XPS, SEM, TEM, UV-Vis-DRS, and PL. Rhodamine B (RhB) and 4-nitrophenol (4-NP) are used as the model pollutants for evaluating the photocatalytic activities of AIS and Co-AIS. The optimal doping ratio of Co?In is found to be 10.7:6.3. And, under this optimal ratio, Co-AIS can degrade 95 % of RhB in 1.5 h or 76 % of 4-NP in 2.5 h, respectively. The photocatalytic mechanism is proposed based on the active species trapping experiment, EPR technique, optical properties characterization, and the flat-band potential determination. Moreover, the photocatalytic water splitting performance of Co-AISs with or without the modification of the multi-walled carbon nanotubes (MWCNTs) are investigated, and remarkable hydrogen production is achieved. This research will open a new gateway to synthesizing AgInS2-based materials and exploring their photocatalytic activities.
查看更多>>摘要：? 2022 Elsevier B.V.Owing to the rapid development of future technologies, IoT, actuators, and sensors inside robots have attracted much attention. Among the actuator materials, ferromagnetic shape memory alloys (FSMA), whose shape change could be manipulated by controlling its temperature, stress, and/or magnetic-field, are considered to be appropriate actuator materials. Besides, FSMA further possesses high work/volume ratio and fast response further allowing it a promising actuator material. Polycrystalline and single crystalline Ni-Mn-Ga alloys were successfully fabricated by arc-melting and floating-zone methods, respectively. Phase constituents of the Ni-Mn-Ga alloys were verified to be the single 5-modulated (5M) martensite phase, whose martensite variant reorientation (MVR) could be triggered by either applying an external magnetic field or a stress field. An in-situ observation of the martensitic transformation from 373 K to 273 K was clearly revealed. The MVR of the Ni-Mn-Ga alloy driven by an external magnetic field was also confirmed. Besides, typical stress plateau was discerned while a compressive stress was applied to the Ni-Mn-Ga alloy. Effects of ratios of the Ni-Mn-Ga alloy to the silicone rubber showed a good correlation and has been well-explained. Furthermore, it was found that a threshold range of approximately 7 vol.%?13 vol.% of the Ni-Mn-Ga alloy is the lowest requirement for the commencement of MVR.
查看更多>>摘要：? 2022 Elsevier B.V.The development of stable, efficient photocatalyst for environmental antibiotics degradation is great significant and remains a major challenge. Herein, novel 2D/0D n-MoSSe/p-Co3O4 Z-scheme heterojunction catalysts (MSCO) are developed to combine the advantages of n-type MoSSe nanoplates and p-type Co3O4 nanoparticles. With an optimized Co3O4 loading ratio, the MSCO2 sample exhibited 7.8 and 28.8 times of photocurrent density more than that of pure MoSSe and Co3O4, and likewise showed 2.54 and 8.91 times of photocatalytic tetracycline hydrochloride removal rate more than that of pure MoSSe and Co3O4. Moreover, the heterojunction displayed outstanding recyclability after five cycles. The remarkably enhanced catalytic properties were mainly ascribed to the 2D/0D structure, built-in electric field between p-n heterojunction and electron transfer the Z-Scheme pathways which was helpful to promote the separation of photogenerated carriers. Additionally, the corresponding reaction pathway and photocatalytic mechanism were further elucidated by the results of the electron spin resonance (ESR) and high-pressure liquid chromatography-mass spectrometry (HPLC-MS). This research provided a new idea for the construction of Z-Scheme p-n heterojunction with 2D/0D structure in photocatalysis, photoelectrochemistry, and electrocatalysis.
查看更多>>摘要：? 2022 Elsevier B.V.Asymmetric hybrid supercapacitors (AHSs) with wide operating voltage windows can be developed by effectively combining electric double-layer capacitor- and battery-type electrodes while maintaining their excellent cycling stabilities. In this study, the hybridization of two-dimensional Cu–Cr phosphate (CCP) with layered reduced graphene oxide (rGO) is achieved to develop a high-performance AHS. CCP and rGO are combined into CCP/rGO (CCPG) nanohybrids by a simple and inexpensive single-step chemical method. The CCPG nanohybrids prepared with an optimal amount of rGO exhibit mesoporosity with high surface areas (40 m2/g) and fast charge transfer kinetics. The optimized CCPG delivers a higher specific capacity of 1620 C/g than CCP (694 C/g) in a three-electrode configuration at a current density of 1 A/g. When fabricated using the CCPG and rGO, the AHS exhibits a high specific capacity of 177 C/g, high specific energy of 65.14 Wh/kg, high specific power of 826 W/kg at 1 A/g, and outstanding cyclic stability (94%) within the widened potential window (1.6 V) in aqueous electrolyte. This study suggests that conducting rGO plays a crucial role in the formation of high-performance CCPG nanohybrids, and consequently, the resulting CCPG electrode demonstrates considerably enhanced physiochemical and electrochemical properties, compared with the CCP electrode. Through this hybridization approach, various nanohybrids of other metal dichalcogenide phosphates and rGO can also be developed.
查看更多>>摘要：? 2022 Elsevier B.V.In this paper, a novel surface-doped Fe-Bi2SiO5 photocatalyst was synthesized by the oil bath method for the first time. Compared with the pure Bi2SiO5, the degradation rate constants of the FB-2 (the mole ratio of Fe/Bi was 1.7%) were increased by 3.8 and 5 times for Ciprofloxacin (CIP) and Rhodamine B (RhB), respectively. In addition, the results of the total organic carbon (TOC) test manifested that the mineralization capacity of FB-2 for CIP and RhB were increased to 40.7% and 64.7%, respectively. Moreover, the effects of catalyst dosage, initial solution concentration, initial pH and inorganic anions on photocatalytic performance were studied. The cyclic degradation experiments of FB-2 verified the excellent stability of photocatalysts, while active species trapping experiments and electron spin resonance (ESR) tests showed that superoxide radicals and holes played a major role in the degradation process. The paper presented that the photocatalytic activity of Bi-based photocatalysts was improved by a surface modified method, which provided a new idea for further study.
查看更多>>摘要：? 2022Two-dimensional (2D) nanosheets show great potential for gas sensing, but they can hinder the penetration of gas molecules and lead to deteriorated sensing performances. Hence, construction of 2D nanosheet-based gas sensing materials with unique structures is desirable for high-performance gas sensing. Herein, a three-dimensional (3D) binary nanosheet heterostructure based on 3D cobalt sulfide (CoS) nanoflower/graphene nanosheet hybrid was constructed for room-temperature NO2 gas sensing. The 3D CoS/reduced graphene oxide (rGO) hybrid derived from a mixture of Co3O4 nanoflowers and graphene oxide nanosheets was facilely formed via in-situ sulfidation and reduction processes. The resistance response of as-assembled gas sensor based on 3D CoS nanoflower/graphene nanosheet hybrid to 1 ppm NO2 was 39.7%, which was 4.2 and 3.1 times higher than that of CoS and rGO sensors, respectively. A response as high as 10.5% was achieved even when the device was exposed to NO2 gas with a low concentration of 50 ppb. Furthermore, the hybrid device exhibited linear response characteristic, high selectivity, good repeatability, as well as long-term stability. Overall, the proposed design strategy together with the as-constructed structures can pave the way for the development of high-performance gas sensors based on graphene hybrids.
查看更多>>摘要：? 2022Samarium-cobalt (Sm-Co) sintered magnets have high magnetic energy densities, great resistance to demagnetization and corrosion, and excellent thermal stability in a wide temperature range (–50–550 °C). However, the utilization of these magnets is restricted by their brittleness. Based on micromechanical and the Zener pinning model, Sm-Co sintered magnets with improved mechanical properties have been designed and fabricated via microstructure engineering. A small amount of fine Sm2O3 particulates (0–3 wt%) has been incorporated into Sm2(CoFeCuZr)17 sintered magnets to refine the grain size by up to approximately 50% (from 45 to 22 μm) and narrow the grain size distribution. Doping with 3 wt% Sm2O3 increased the flexural strength by 62% while maintaining magnetic performance. Both grain-refined unimodal microstructure and heterogeneous laminated coarse/fine grain microstructure were formed by strategically designed assemblies of Sm2O3-added Sm-Co powder feedstock mixtures. The technology is compatible with existing magnet manufacturing processes. Numerical micromechanics simulation indicates that the fracture is dominated by intragranular mode. The mechanical strength is mainly enhanced by the additive-induced grain refinement, while the small amount of Sm2O3 addition has a small direct positive contribution. These magnets will be more cost-effective, efficient, and robust for various functional applications.
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