HF Etching-Enabled In Situ Growth of a Robust NiFe Prussian Blue Analogue Derivative as an Integrated Electrode for an Efficient Oxygen Evolution Reaction

NiFe-based Prussian blue analogue (PBA) derivatives have attracted significant attention as electrocatalysts for the oxygen evolution reaction (OER) in water splitting. However, efficiently in-situ constructing integrated PBA electrodes under mild synthesis conditions continues to be a great challenge. In this study, a porous honeycomb-like NiFe PBA derivative was successfully constructed on nickel foam (NF) via mild HF etching and controlled pyrolysis. Owing to the complexing corrosion between Ni and HF, the generation of Ni2+ ions will continue unabated, which promotes the nucleation of the NiFe PBAs (Ni3[Fe(CN)6]2). Simultaneously, polyvinylpyrrolidone (PVP), as a structure-directing agent, provides favorable conditions for the formation of the desired honeycomb-like product. The optimized catalyst (abbreviated as F/0.1-NiFe PBAs-300, where 0.1 and 300 represent HF concentration and pyrolysis temperature, respectively) demonstrates an outstanding OER performance with an overpotential of 273 mV at 10 mA cm–2 and excellent durability over 120 h in 1.0 M KOH aqueous solution, surpassing commercial RuO2. This work offers a feasible strategy for designing high-performance PBA-derived integrated electrode with the potential to replace noble-metal-based OER electrode.