One-step solvothermal growth of NiO nanoparticles on nickel foam as a highly efficient electrocatalyst for hydrogen evolution reaction

Herein we report for the first time on the in situ solvothermal growth of NiO nanoparticles on nickel foam (NF) electrodes towards enhancing the active electrochemical area and, in turn, the hydrogen evolution reaction (HER). In particular, the Ni amount deposited on the NF electrode was thoroughly explored by varying the Ni precursor content (0–64 mmol of Ni(NO3)2·6H2O) during one-step solvothermal synthesis. A volcano-type dependency on Ni precursor amount was revealed, with the optimum performance being obtained by NiO@NF-16 (16 mmol Ni(NO3)2·6H2O). The NiO@NF-16 sample exhibited the lowest overpotentials |η10| = 109 mV, |η100| = 193 mV, the lowest Tafel slope (103.9 mV dec−1), and the highest current density during electrolysis (1947 mA cm−2). To gain insight into structure-performance relationships, the electrodes were thoroughly characterized by means of field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). It was revealed that the improved electrochemical characteristics of NiO@NF-16 electrode could be mainly attributed to the uniform growth and high dispersion of NiO nanoparticles on nickel foam, which, in turn, results in a high electrochemically active surface area (ECSA), which is ca. 55 times higher than that of NF electrode.