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Ag-Zn alloys are identified as highly active and selective electrocatalysts for CO2 reduction reaction (CO2RR), while how the phase composition of the alloy affects the catalytic performances has not been systematically studied yet. In this study, we fabricated a series of Ag-Zn alloy catalysts by magnetron co-sputtering and further explored their activity and selectivity towards CO2 electroreduction in an aqueous KHCO3 electrolyte. The different Ag-Zn alloys involve one or more phases of Ag, AgZn, Ag5Zn8, AgZn3, and Zn. For all the catalysts, CO is the main product, likely due to the weak CO binding energy on the catalyst surface. The Ag5Zn8 and AgZn3 catalysts show a higher CO selectivity than that of pure Zn due to the synergistic effect of Ag and Zn, while the pure Ag catalyst exhibits the highest CO selectivity. Zn alloying improves the catalytic activity and reaction kinetics of CO2RR, and the AgZn3 catalyst shows the highest apparent electrocatalytic activity. This work found that the activity and selectivity of CO2RR are highly dependent on the element concentrations and phase compositions, which is inspiring to explore Ag-Zn alloy catalysts with promising CO2RR properties. [ABSTRACT FROM AUTHOR]

This study reports a unique binder-free nickel oxalate (NiC2O4) nanodiamond-decorated Ni foam which is fabricated through anodization, as a new-type electrode material for nonenzymatic glucose biosensing. The electrode presents multilinear detection ranges with ultrahigh sensitivities (up to 144.26 mA m m−1 cm−2) and an ultralow detection limit (5 × 10−9 m), as well as acceptable selectivity and stability toward glucose detection. The superior sensing performance not only originates from the electrochemical catalytic activity of NiC2O4 nanodiamonds, but also associates with its in situ growth on the skeleton of Ni foam, making full use of the high conductivity of the metal substrate and the direct interface contact between the two materials and concurrently promoting superior electronic/ion conductivity of the whole electrode. Besides, a new method to determine the turnover frequency is introduced to evaluate the intrinsic chemical properties of biochemical catalysts for glucose detection. This is the first attempt to systematically illustrate that nickel oxalate can also be applied to the electrochemical oxidation of glucose. More significantly, the findings can direct the fabrication of many other oxalate-based nanostructured glucose biosensors with high performance. [ABSTRACT FROM AUTHOR]

Low electronic conductivity and drastic volume change during cycling of transition metal oxides, as anodes for lithium ion batteries (LIBs), lead to rapid capacity decay and poor structural stability. Herein, nanostructured NiCo 2 O 4 anchored on carbon sheets was synthesized by a facile hydrothermal method with following thermal treatment. The wrinkled carbon substrate in the composite derives from the carbonization of pomelo peels, which can be mass-produced for the large-scale application. This composite shows mesoporous structures with high specific surface areas and intimate NiCo 2 O 4 /carbon interfaces, which favors the alleviation of the volume expansion/shrink during charging/discharging process and improves the electron/mass transport, enhancing the capability and stability for LIBs. This composite delivers a high reversible capacity of 473.7 mA h g−1 after 210 cycles at a current density of 500 mA g−1. A long cycle life of up to 1100 cycles at 2000 mA g−1 is achieved with the retention capacity of 363 mA h g−1. The electrode also exhibits excellent rate capability and can regain its original capacities as reversing to the low current densities. This work highlights the biomass-derived carbon-supported metal oxides as an environmentally friendly and economic strategy for advanced LIBs. • Carbon substrate as buffer for anode materials can be derived from pomelo peels. • Cycling stability of NiCo 2 O 4 is improved by depositing it on carbon substrate. • Faster Li+ diffusion coefficients are obtained with the existence of carbon. [ABSTRACT FROM AUTHOR]