Design of NiCo2O4@NiMoO4 core-shell nanoarrays on nickel foam to explore the application in both energy storage and electrocatalysis

NiCo2O4@NiMoO4 core-shell nanowires (NCNMW) and nanosheets (NCNMS) with high electrochemical capabilities were synthesized using a simple two-step hydrothermal reaction, together with a calcination process. As active electrode materials, all of the prepared electrodes were tested in a three-electrode system. Among all the electrodes, NCNMS-2 exhibited a large specific capacity (1770.95 C g(-1) at a current density of 3 mA cm(-2)), a high-rate capability (1334.18 C g(-1) at 40 mA cm(-2)), and superior cycling stability (102.78% capability retention after 5000 cycles at 10 mA cm(-2)). The NCNMS-2//activated carbon battery-supercapacitor hybrid device yielded a high energy density of 30.57 W h kg(-1) at a power density of 676.06 W kg(-1) and excellent stability with a capacitance retention of 92.71% after 5000 continuous cycles at a current density of 10 mA cm(-2). In addition, as an electrocatalyst for the oxygen evolution reaction (OER), the NCNMS-2 exhibited a small Tafel slope of 59 mV Dec(-1), and a low overpotential of 175 mV at a current density of 10 mA cm(-2). The excellent electrochemical performance of the hierarchical NiCo2O4@NiMoO4 structure was attributed to its porosity and the characteristics of the 3D nanostructure subunits that possess many active reaction sites, rapid electron/ion transport, and high stability. Based on the excellent electrochemical properties, it will serve well for energy storage and conversion.

Automated summary

NiCo2O4@NiMoO4 core-shell nanowires and nanosheets with high electrochemical capabilities were successfully synthesized. These materials exhibited large specific capacity, excellent cycling stability, and high-rate capability, making them promising candidates for energy storage and electrocatalysis.