Dual-Engineered Fe-Doped NiCo₂S₄/Carboxymethylcellulose Aerogel as Efficient and Robust Electrocatalyst for Oxygen...

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 NiCo₂S₄/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 Ni³⁺ and Co²⁺ 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-NiCo₂S₄/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.