Optimizing Nickel-Based Electrocatalysts for Hydrogen and Oxygen Evolution: Electronic and Geometric Perspectives.

Electrochemical water splitting is a promising approach for sustainable hydrogen production, yet the development of cost-effective and efficient electrocatalysts remains a critical challenge. Nickel-based materials have emerged as viable alternatives to noble metal catalysts due to their abundance, tunable electronic structure, and comparable catalytic activity. This review systematically summarizes recent advances in nickel-based electrocatalysts for hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and overall water splitting (OWS). Based on the catalytic mechanism of the above reactions, electronic structure modulation from a thermodynamic adsorption/desorption optimization perspective and geometric structure optimization from a diffusion kinetic improvement perspective are proposed for a high-performance Ni-based electrocatalyst. Key strategies include morphology engineering, alloying, heteroatom doping, phase engineering, and heterostructure construction, which optimize intermediate adsorption/desorption, charge transfer, and mass transport kinetics. Despite significant progress, challenges persist in achieving industrial-scale current densities (>500 mA cm^-2) and long-term stability. Future efforts should focus on multiscale design, high-current-density testing, and mechanistic studies to bridge the gap between laboratory research and practical applications. This review provides valuable insights for designing highly efficient Ni-based electrocatalysts toward scalable green hydrogen production.