Constructing Synergistic Manganese−Prussian Blue Analogue Intercalated into Nickel Hydroxide Bifunctional Catalyst Enables Overall Water Splitting in Alkaline Medium

Abstract

Electrochemical water splitting (EWS) has emerged as a promising and sustainable approach for high-purity hydrogen production, offering an effective pathway toward clean and renewable energy conversion. However, the sluggish reaction kinetics of the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) demand the development of highly efficient and cost-effective bifunctional electrocatalysts based on earth-abundant materials. Herein, a manganese−cobalt Prussian blue analogue (MC-PBA) intercalated nickel hydroxide (NiOH) heterostructure was rationally engineered through a facile synthetic strategy to enhance alkaline water-splitting performance. The robust electronic interaction between MC-PBA and NiOH modulates the electronic structure of the active centers, accelerates interfacial charge transfer, and improves the adsorption/desorption energetics of catalytic intermediates. In addition, the intercalated heterostructure offers abundant exposed electroactive sites, improved electrolyte accessibility, and rapid ion diffusion pathways, thereby facilitating enhanced electrocatalytic kinetics. Consequently, the optimized MC-PBA@NiOH catalyst accomplishes low overpotentials of ∼740 mV for OER and ∼585 mV for HER at 100 mA cm−2, together with small Tafel slopes of 179 and 127 mV dec−1, respectively. Furthermore, the assembled alkaline electrolyzer involves a low cell voltage of 2.71 V to deliver 100 mA cm−2 with excellent long-term operational stability. The superior bifunctional catalytic activity originates from the synergistic coupling between the redox-active MC-PBA framework and conductive NiOH matrix, which collectively promotes electron-transfer kinetics and intrinsic catalytic activity. This work reveals an effective heterointerface engineering strategy for the development of progressive nonprecious electrocatalysts for efficient overall water splitting and sustainable hydrogen generation.