Developing Ni3N/NiO Heterostructure Catalysts to Enhance Hydrogen Evolution Reaction in Alkaline Medium via a Surface-Dependent Mechanism

Abstract

In the construction of sustainable energy systems, the development of efficient and stable electrocatalysts for the hydrogen evolution reaction (HER) is of crucial significance. This study adopts an in-situ oxidation-nitridation strategy to successfully construct a Ni₃N/NiO heterostructured catalyst with a three-dimensional hierarchical structure. In this catalyst, NiO promotes the dissociation of water molecules, while Ni3N facilitates the generation and release of hydrogen molecules. The functional differentiation between these two materials at the interface drives the hydrogen spillover effect, synergistically accelerating the reaction rates of the basic steps in HER. Through electrochemical testing, it is found that Ni₃N/NiO/NF exhibits excellent HER performance in 1.0 M KOH solution, requiring only 58 and 98 mV overpotentials to achieve current densities of 10 and 100 mA cm^-2 , respectively, with a low Tafel slope of 42 mV dec^-1 . Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) analyses confirm the enhanced capability of this heterostructure in hydrogen adsorption and desorption. Ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS) tests reveal electron rearrangement at the interface, verifying the existence of hydrogen spillover pathways. Additionally, the superhydrophilic-superaerophobic wetting characteristics of the catalyst surface help improve the diffusion rate of reactants and the desorption efficiency of products, thereby further enhancing the overall catalytic stability.