RESUMO
ZnWO4@NiCo2O4 core-shell nanosheet array composites are synthesized on nickel foam via a two-step hydrothermal method. The optimal conditions, including a Ni(NO3)2·6H2O to Co(NO3)2·6H2O molar ratio of 2 : 1, 12 hours reaction time, and 120 °C temperature, yield a specific capacitance of 875 C g-1 at 1 A g-1. The electrode also maintains 81.1% capacitance after 10 000 cycles. The material's performance is attributed to its core-shell structure, which enhances ion diffusion and electron transport. This study presents a viable approach for high-performance supercapacitor electrodes.
RESUMO
The electrocatalytic performance of a Fe65Co10Si12.5B12.5 Fe-based compounds toward alkaline hydrogen evolution reaction (HER) is enhanced by dealloying. The dealloying process produced a large number of nanosheets on the surface of NS-Fe65Co10Si12.5B12.5, which greatly increased the specific surface area of the electrode. When the dealloying time is 3 h, the overpotential of NS-Fe65Co10Si12.5B12.5 is only 175.1 mV at 1.0 M KOH and 10 mA cm-2, while under the same conditions, the overpotential of Fe65Co10Si12.5B12.5 is 215 mV, which is reduced. In addition, dealloying treated electrodes also show better HER performance than un-dealloying treated electrodes. With the increase in Co doping amount, the overpotential of the hydrogen evolution reaction decreases, and the hydrogen evolution activity is the best when the addition amount of Co is 10%. This work not only provides a basic understanding of the relationship between surface activity and the dealloying of HER catalysts, but also paves a new way for doping transition metal elements in Fe-based electrocatalysts working in alkaline media.
RESUMO
It is essential for energy storage and conversion systems to construct electrodes and electrocatalysts with superior performance. In this work, ZnCo2S4@Ni(OH)2 nanowire arrays are synthesized on nickel foam by hydrothermal methods. As a supercapacitor electrode, the ZnCo2S4@Ni(OH)2 structure exhibits a specific capacitance of 1,263.0C g-1 at 1 A g-1. The as-fabricated ZnCo2S4@Ni(OH)2//active carbon device can achieve a maximum energy density of 115.4 Wh kg-1 at a power density of 5,400 W kg-1. As electrocatalysts, the ZnCo2S4@Ni(OH)2 structure delivers outstanding performance for oxygen evolution reaction (an overpotential of 256.3 mV at 50 mA cm-2), hydrogen evolution reaction (141.7 mV at 10 mA cm-2), overall water splitting (the cell voltage of 1.53 V at 50 mA cm-2), and a high stability for 13 h.
RESUMO
Bulk metallic glasses exhibit high strength and large elastic strain limit but have no tensile ductility. However, bulk metallic glass composites reinforced by in-situ dendrites possess significantly improved toughness but at the expense of high strength and large elastic strain limit. Here, we report a bulk metallic glass composite with strong strain-hardening capability and large elastic strain limit. It was found that, by plastic predeformation, the bulk metallic glass composite can exhibit both a large elastic strain limit and high strength under tension. These unique elastic mechanical properties are attributed to the reversible B2âB19' phase transformation and the plastic-predeformation-induced complicated stress state in the metallic glass matrix and the second phase. These findings are significant for the design and application of bulk metallic glass composites with excellent mechanical properties.
