Rich Oxygen Vacancies Induced by Surface Self-Reconstruction in Sandwich-like Hierarchical Structured Electrocatalyst for Boosting Oxygen Evolution Reaction

The oxygen evolution reaction (OER) is pivotal in hydrogen production via water electrolysis, yet its sluggish kinetics, stemming from the four-electron transfer process, remain a major obstacle, with overpotential reduction being critical for enhancing efficiency. This work addresses this challenge by developing a novel approach to stabilize and activate non-precious metal catalysts for OER. Specifically, we synthesized a three-dimensional flake NiFe-LDH/ZIF-L composite catalyst on a flexible nickel foam (NF) substrate through a room temperature soaking and hydrothermal method, leveraging the mesoporous structure of ZIF-L to increase the specific surface area and optimizing electron transfer pathways via interfacial regulation. Continuous linear sweep voltammetry (LSV) scanning induced structural self-reconstruction, forming highly active NiOOH species enriched with oxygen vacancies, which significantly boosted catalytic performance. Experimental results demonstrate an overpotential of only 221 mV at 10 mA cm^-2 and a Tafel slope of 56.3 mV dec^-1, alongside remarkable stability, attributed to the catalyst's hierarchical nanostructure that accelerates mass diffusion and charge transfer. The innovation lies in the synergistic effect of the mesoporous ZIF-L structure and interfacial regulation, which collectively enhance the catalyst's activity and durability, offering a promising strategy for advancing large-scale water electrolysis hydrogen production technology.