Phase-Controlled Synthesis And The Phase-Dependent Her And Oer Performances Of Nickel Selenide Nanosheets Prepared By An Electrochemical Deposition Route

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.