Sulfidation-modulated high-entropy Prussian blue analogues for enhanced oxygen evolution electrocatalysis

The development of efficient and durable electrocatalysts for the oxygen evolution reaction (OER) remains a critical challenge for water splitting due to the sluggish reaction kinetics and limited catalyst durability. Herein, we report a facile two-step electrodeposition strategy to fabricate a sulfidation-modulated high-entropy Prussian blue analogue directly on carbon paper (HE-PBA-S/CP) as an efficient self-supported OER electrocatalyst. The high-entropy PBA serves as a compositionally complex multimetal precursor, while thiourea-assisted sulfidation modulates the surface/interface characteristics and electronic environments of the constituent metal centers, substantially increasing the electrochemically accessible interface and facilitating the formation of catalytically active multimetal oxyhydroxide species during the OER. As a result, the optimized HE-PBA-S/CP catalyst requires an overpotential of only 167 mV to deliver a current density of 10 mA cm^-2 together with good stability for 120 h at 100 mA cm^-2 in alkaline media, significantly outperforming the pristine HE-PBA/CP catalyst and its composition-controlled sulfidation-modulated PBA counterparts. This work highlights the integration of high-entropy precursor design and sulfidation-assisted surface/interface modulation as an effective strategy for the rational design of cost-effective and high-performance electrocatalysts for water splitting.