Engineering electron redistribution of CeO2/Ni(OH)2@Mo-NiS nanorod composites with rich oxygen vacancies for overall water splitting.

Abstract

As a clean energy source with high calorific value and clean products, the research and development of electrocatalysts for overall water splitting is a crucial step. In this study, a Mo-doped NiS modified CeO₂/Ni(OH)₂ nanorod with oxygen-rich vacancies (CeO₂/Ni(OH)₂@Mo-NiS) was synthesized by hydrothermal method. The strong hybridization between Ni-3d and O-2p orbitals at deep energy levels can achieve overall metallic properties. Mo doping regulates the charge redistribution near the Fermi level and optimizes the adsorption of intermediates. Furthermore, the presence of oxygen vacancies facilitates to accelerate electron transfer. Hence, in 1 mol/L of KOH electrolyte, CeO₂/Ni(OH)₂@Mo-NiS-2 requires only an overpotential of 111 mV and 280 mV to achieve a current density of 10 mA cm^-2 for hydrogen evolution reaction (HER) and 50 mA cm^-2 for oxygen evolution reaction (OER), respectively. When used as both cathode and anode as a bifunctional catalyst for overall water splitting, only 1.62 V was required to achieve a current density of 10 mA cm^-2.