查看更多>>摘要：In this work, we report a simple one-step hydrothermal synthesis strategy for depositing edge-rich MoS2 nanosheets on conductive layered Ti3C2 MXene, and demonstrate the formed MoS2/Ti3C2 heterostructure has significant active site exposure and effective charge carrier flow. The resulting MoS2/Ti3C2 exhibits enhanced activity and excellent stability for the catalytic reduction of 4-nitrophenol (4-NP). The optimal MoS2/Ti3C2 catalyst displays a high pseudo-first-order rate constant of 0.61 min?1, a conversion efficiency of 96.2% within 5 min and almost unchanged activity after six consecutive reaction cycles, which is better than the pristine MoS2 nanosheets. Moreover, the MoS2/Ti3C2 catalyst achieves a pseudo-first-order rate constant as high as 0.779 min?1 for the catalytic reduction of methylene blue (MB). This study opens up new opportunities for the design and development of cost-effective, efficient and reusable alternatives to noble metal catalysts based on molybdenum disulfide for environmental applications.
查看更多>>摘要：Vanadium-based MXenes are prospective as anode materials in energy-storage devices including lithium-ion batteries (LIBs) but limited by their charge-discharge capacities. Herein, partially-etched V2AlxCTz with the average particle size of ~400 nm was synthesized using 40 wt% HF or mixed NaF+HCl solutions as etchants, respectively. V2AlxCTz etched by 40 wt% HF for 96 h at room temperature (RT) has more exceptional charge-discharge performances against mixed NaF+HCl solutions, with an average reversible capacity of ~450 mAh g?1 at 0.1 A g?1 in the 120 cycles and ~301.2 mAh g?1 at 0.5 A g?1 after 200 cycles in LIBs. The effect of etchants on electrochemical performances and lithium-ion (Li-ion) storage mechanism of V2AlxCTz was discussed comprehensively. Additionally, a Li-ion full cell using LiFePO4 as cathode has exhibited excellent electrochemical performance (150.4 mAh g?1 at 0.1 C). This work illustrates that partially-etched V2AlxCTz with the submicro-sized distribution is also a promising anode material for LIBs.
查看更多>>摘要：Because of its low cost and high energy density, Na-based dual-ion batteries (Na-DIBs) have attracted more and more research and technical attention, providing broad prospects for emerging energy storage and conversion applications. However, developing advanced anodes for Na-DIBs with high energy density, long cycle life and high power density remains challenging. Here we demonstrate a facile strategy to synthesize KMF3 (M = Ni or Co)@reduced graphene oxide (recorded as KMF3 (M = Ni or Co)@rGO or Ni-G and Co-G) by a one-pot method. The Ni-G and Co-G electrodes exhibit a pseudocapacitive kinetics and a typical highly reversible conversion reaction mechanism by cyclic voltammetry (CV) and ex situ X-ray photoelectron spectroscopy (XPS). Further assembled with KS6 to form Na-DIBs, Ni-G//KS6 and Co-G//KS6 deliver high energy density (328.8 W h kg?1 and 187.6 W h kg?1), high power density (18.29 kW kg?1 and 21.62 kW kg?1) and cycle life over 1000 cycles. Moreover, these devices work well at ? 20 to 40 °C. This work discusses new insights into perovskite fluoride as Na-DIBs, providing a strategy for high-energy-density and long-cycle energy storage systems.
查看更多>>摘要：Li7La3Zr2O12 (LLZO), a kind of solid-state electrolyte possessing the potential to realize an all-solid-state battery, attracts lots of attention. The Sr2+ and Mo6+ are co-doped into LLZO to obtain Li6.6+xLa3?xSrxZr1.8Mo0.2O12, in which x varies from 0 to 0.2. The strategy of doping Mo6+ into Zr4+-site can effectively ensure the formation of the cubic phase. On the basis of Zr4+-site doping method, doping appropriate Sr2+ can further improve the ionic conductivity and the relative density of the sample. A low temperature of 1100 °C and the cold pressing sintering method are applied. Through X-ray diffraction (XRD), Raman spectrum, inductively coupled plasma-optical emission spectroscopy (ICP-OES) and scanning electron microscope (SEM), we further discuss the mechanism of doping elements into lattice of LLZO. When x = 0.05, the sample Li6.65La2.95Sr0.05Zr1.8Mo0.2O12 exhibits the ionic conductivity of 6.43 × 10?4 S cm?1 (the highest among the works which used single Sr2+ or Mo6+ to dope LLZO) and the relative density of 95%.
查看更多>>摘要：From the perspective of sustainability, using biomass waste to synthesize hierarchical interconnected porous carbon (HIPC) for long-life and high-energy/power density supercapacitors are a research hotspot. Here, waste peach gum and other green resources are transformed into N, P co-doped and O-rich layered interconnected porous carbon through impregnation and carbonization processes. Thanks to the multiple synergistic effects originated from a high specific area (1635 m2 g?1) and a suitable N, P co-doped content, the HIPC electrode materials exhibits an excellent electrochemical performance with a high specific capacitance (490 F g?1 under 1 A g?1) and superior rate capability. More importantly, the maximum energy density of the assembled symmetrical supercapacitor can reach a power density of 76.87 Wh kg?1 at 799.8 W kg?1, and delivers an excellent cycle life (the capacitance loss rate after 10,000 cycles is only 10.1%). Moreover, the optimum samples of HIPC exhibit satisfactory rate stability at different scan rates. This work provides an efficient and economical strategy for energy storage and renewable delivery devices.
查看更多>>摘要：To improve the cell performance, CH3NH3PbI3 film prepared via a two-step method in air was modified by Co2+ doping and magnetic field action. Effects of Co2+ doping and magnetic field strength on film properties and cell performance were investigated. Possible influence mechanisms of Co2+ doping and magnetic field strength on perovskite structure, film properties and cell performance were studied. Results show that Pb in CH3NH3PbI3 was partially replaced by 10% Co, and Co2+ doped device exhibits ameliorative stabilities and efficiency compared with undoped one due to the more stable [Pb(Co)I6]4- octahedron structure and the suppression of ion migration, respectively. Then, weak magnetic field action furtherly improves stability and efficiency of CH3NH3Pb0.9Co0.1I3 based cell by furtherly stabilizing [Pb(Co)I6]4- octahedron structure and inhibiting ion migration, separately. This work has proposed a novel theory for magnetic field action influencing the performance of magnetic ions doped perovskite solar cells and offered a new idea for preparing cells with improved performance, which is helpful to facilitate the commercialization of perovskite solar cells.
查看更多>>摘要：In this work, five AZ31-xCe magnesium alloy anode materials were prepared, and their microstructure, electrochemical properties and discharge properties were studied to reveal the effect of Ce content on the casting anode of magnesium air battery. The introduction of the Ce element can refine the grain and purify the α-Mg matrix. AZ31–1Ce magnesium alloy has the best corrosion resistance, and the activity of magnesium alloy enhances with the increase of Ce content. Compared with AZ31 magnesium alloy, AZ31-xCe magnesium alloy has higher discharge activity, which is due to the introduction of Ce element to purify the magnesium alloy, and the Al4Ce phase can promote the uniform dissolution of Mg matrix. When the discharge current density is 10 mA cm?2 the AZ31–4Ce anode shows the highest energy density of 1552.370 mWh g?1 and the best specific capacity of 1282.051 mAh g?1 which are 46.05% and 29.901% higher than the AZ31 anode. Compared with AZ31 magnesium alloy, the anode of AZ31–4Ce magnesium alloy has a smoother discharge surface morphology, which is beneficial to the desquamation of the discharge products.
查看更多>>摘要：In the present work, textured stoichiometric MnCoSi alloys were fabricated by slow-cooling thermal treatment. Microstructure and crystallographic characterization revealed that the textured MnCoSi alloy consists of three different oriented orthorhombic TiNiSi-type martensite variants with their aOrth-axis lying in the cross-section of the rod-like MnCoSi alloy. A giant reversible linear negative thermal expansion (NTE) as much as 9350 ppm was achieved along the aOrth-axis of the textured MnCoSi alloy at a wide operation temperature span from 50 K to 400 K, owing to the antiferromagnetic arrangement. The linear NTE value slightly decreases from 9350 ppm to 9200 ppm with increasing the external magnetic field up to 2 T, which indicates that the present MnCoSi alloy demonstrates a stable NTE effect under external magnetic field. Moreover, during the martensitic transformation, the linear NTE along the aOrth-axis of the textured MnCoSi alloy could be up to 70,000 ppm at about 1200 K.
查看更多>>摘要：The anisotropic BaFe12?xCoxO19 (x = 0, 0.3, 0.6, 0.9) (BFCO) samples were synthesized. We investigated the crystal structure, microstructure, and magnetic properties of BFCO. And the potential application value at millimeter waveband was discussed. The magnetic anisotropy field is successfully decrease from 17 kOe to 10 kOe by substituting Cobalt, which lower the Ferromagnetic resonance frequency and benefit for extending the bandwidth for the circulator. With the cobalt substitution, the saturation inevitably decreases from 60 emu/g to 45 emu/g. The site preference of cobalt in five crystallographically inequivalent Fe ions was calculated using software castep. The influence of site preference on lattice parameters and magnetic saturation was calculated and discussed. The result show cobalt mainly sites 2a and 12k position.
查看更多>>摘要：The Ce-contained dual-main-phase magnets that the (BH)max is 40.39 MGOe, and Hcj increases to 16.61 kOe get well magnetic properties by grain boundary diffusion. The Hcj increases by about 45.7% compared to the sintered state magnets. The XRD shows that RE-O-F compounds are formed in the diffused surface, the characteristic peak is distinct respectively. The gradient distribution structure of the anisotropic field (GDSAF) appears in SEM due to diffusing. Compared with the original (Nd, Ce)-Fe-B grains, EBSD shows that the Exp. Densities (mud) in the direction of {002} of Ce2Fe14B main-phase keep better in diffused magnets. The texture of Ce2Fe14B main-phase is changed from ring-like to the ring, the max value of Exp. Densities (mud) in the direction of {002} in the pole figure gets tremendously improvement. According to the variation of orientation distribution, in terms of elements distribution, the large difference is that whether Tb atoms diffuse into RE2Fe14B main-phase forming GDSAF.
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