Dual‐Engineered Fe‐Doped NiCo ₂ S ₄ /Carboxymethylcellulose Aerogel as Efficient and Robust Electrocatalyst for Oxygen Evolution Reaction

The development of efficient and durable non‐precious electrocatalysts for the oxygen evolution reaction (OER) is crucial for sustainable hydrogen production. In this study, we developed a Fe‐doped NiCo 2 S 4 /carboxymethyl cellulose (CMC) aerogel composite by a combined solvothermal and sol‐gel approach. Fe doping induces lattice distortion and electron redistribution, increasing the contents of highly active Ni 3+ and Co 2+ species. Concurrently, the three‐dimensional porous network of the CMC aerogel host greatly enhances the exposure of active sites and structural integrity. As a result, the optimal 5% Fe‐NiCo 2 S 4 /CMC aerogel composite catalyst requires an ultralow overpotential of 262 mV to achieve a current density of 10 mA cm −2 in 1.0 M KOH, exhibits a small Tafel slope of 88 mV dec −1 , and, most notably, demonstrates outstanding long‐term stability for over 312 h. This work provides a dual‐optimization strategy—through both electronic modulation and structural engineering—for advancing electrocatalyst design for energy conversion applications.