Phase-controlled synthesis and the phase-dependent HER and OER performances of nickel selenide nanosheets prepared by an electrochemical deposition route

Abstract

Phase-controlled synthesis of nickel selenide nanostructures was successfully realized via a facile electrodeposition route with the same electrolyte at room temperature and by employing a Ni foam (NF) as the substrate and NiCl₂ and SeO₂ as the Ni and Se sources, respectively. The results indicated that pure NiSe₂, NiSe, and Ni₃Se₂ were obtained when the deposition potentials were −0.35, −0.46, and −0.60 V, respectively. The as-obtained products were characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). It was found that nickel selenide nanostructures exhibited clear phase-dependent electrocatalytic activities for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). NiSe₂ presented the best HER and OER performances. The NiSe₂/NF electrode required overpotentials of only 104 mV and 279 mV to obtain the current densities of 10 mA cm⁻² for HER and 20 mA cm⁻² for OER, respectively. Moreover, three nickel selenide/NF electrodes displayed excellent catalytic stabilities.