Fe-doping effect on CoMoO4 for electrochemical oxygen evolution in neutral media

Abstract

As an economically viable and environmentally benign electrocatalyst, CoMoO₄ has emerged as a promising alternative to noble metal-based water oxidation catalysts in recent years. However, the oxygen evolution reaction (OER) under neutral condition presents a significantly greater challenge compared to reactions occurring in acidic or alkaline electrolytes. Therefore, to further enhance the OER activity of CoMoO₄ under neutral conditions, we adopted an Fe-doping strategy. By precisely controlling the synthesis time, we successfully developed a series of Fe-CoMoO-X samples with varying morphologies (where X represents the synthesis time, ranging from 10 to 16 h) for electrocatalytic OER. By integrating multiple material characterization techniques with advanced electrochemical evaluation methods, we confirmed that the synthesis time profoundly influences the morphology of the Fe-CoMoO-X samples, which directly correlates with their catalytic performance for oxygen evolution. Moreover, all Fe-doped samples demonstrate markedly enhanced electrocatalytic activity compared to pristine CoMoO₄. Notably, the Fe-CoMoO-13 h sample exhibits the most superior oxygen evolution performance, achieving an overpotential of only 380 mV at a 10 mA cm⁻² (Tafel slope of 289 mV dec⁻¹), substantially lower than that of pure CoMoO₄ (400 mV at 10 mA cm⁻²; Tafel slope of 403 mV dec⁻¹). This improvement can be attributed to the partial substitution of Co atoms with Fe atoms in the doped CoMoO₄ structure, which modulates its electronic properties and enhances charge transfer kinetics.