MoS x /Fe-Modified Cobalt Layered Double Hydroxide for Applications in the Oxygen Evolution Reaction

Developing efficient, low-cost oxygen evolution reaction (OER) catalysts is essential for advancing water electrolysis toward large-scale application. In this work, a series of layered composite metal hydroxide catalysts with tunable Co–Fe–Mo–S ratios were synthesized via a simple coprecipitation route. The optimized catalysts exhibit a three-dimensional porous network assembled from ultrathin nanosheets with reduced thickness and abundant defects. Among them, the optimized Co 4 Mo 1 S–Fe 0.5 -LDH electrode demonstrated outstanding OER activity in 1 M KOH, achieving a low overpotential of 278 mV at 10 mA cm –2, a Tafel slope of 48.2 mV dec –1, and a high double-layer capacitance of 29.56 mF cm –2 . Notably, the catalyst maintained stable performance over 600 h of continuous operation. The enhanced activity originates from several structural and compositional advantages: the MoS x -induced Mo 6+ /Mo 4+ redox couple promotes charge transfer, while Fe 3+ and Co 3+ species act as synergistic active sites that improve reaction kinetics. DFT calculations reveal that codoping lowers the free energy barrier of the rate-determining step from 1.60 to 1.56 eV. Furthermore, the layered architecture maximizes active site exposure and facilitates electrolyte diffusion. This work offers a feasible strategy for designing high-performance, composition-tunable layered double hydroxide (LDH) catalysts for efficient water oxidation.