Cr-Ni synergy regulating the surface reconstruction of medium-entropy CoFeCrNiO4 to achieve high-performance OER

Spinel oxides are promising electrocatalysts whose activity can be tuned by elemental composition, yet understanding multicomponent synergy remains challenging. Herein, a Spinel-type medium-entropy CoFeCrNiO 4 electrocatalyst is developed, and a Cr-Ni synergistic strategy is proposed to regulate dynamic surface reconstruction during OER. The catalyst exhibits an overpotential of 263.4 mV at 10 mA cm −2 and 365 mV at 300 mA cm −2 in 1 M KOH, with a low Tafel slope of 37.12 mV dec −1 . It also shows excellent stability, with only 2.78% overpotential decay after 24 h operation. In-situ characterization reveals that the Cr-Ni interaction promotes the formation of active oxyhydroxide species during reconstruction. This work provides insights into synergy-driven activity enhancement and offers guidance for the design of high-performance spinel OER catalysts.