Solid-State Engineered Fe-CoMoO₄with 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 CoMoO₄sample 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^–2for 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.