Solid-State Engineered Fe-CoMoO₄ with a Defect-Rich Structure: Trimetallic Synergy for Enhanced Oxygen Evolution Reaction

Developing highly active and stable nonprecious-metal-based electrocatalysts for the oxygen evolution reaction (OER) is essential for advancing clean energy technologies. This study reports a single-step synthesis method that simultaneously introduces significant structural defects and incorporates iron (Fe) dopants in CoMoO4, enhancing OER performance. Comprehensive structural analysis using X-ray diffraction, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy confirms the successful formation of defects and effective iron doping. Morphological analysis via scanning electron microscopy and transmission electron microscopy reveals a nanoplate morphology rich in structural defects, which maximizes the number of electrochemically active sites. The optimized catalyst CFM-500, defined as the Fe-doped CoMoO4 sample calcined at 500 °C, exhibited excellent catalytic performance, as evidenced by an exceptionally low overpotential of 150 mV at a current density of 10 mA cm–2, a low Tafel slope of 41 mV dec–1, a high electrochemically active surface area of 1637 cm2, and stable performance at 100 mA cm–2 for more than 24 h. These outstanding electrochemical characteristics are attributed to the synergistic effects of Fe-induced defect engineering, increased charge transfer kinetics, and the large surface area featured by the nanoplate morphology.