Iron-doped molybdenum carbide for improved reactants adsorption in oxygen evolution reaction

Molybdenum carbide is an excellent HER (Hydrogen evolution reaction) electrocatalyst because of its d-band center and Fermi level, which are similar to the precious metal Pt. However, the main challenge faced by Mo materials in water splitting is the unsatisfactory oxygen evolution reaction (OER) activity. Herein, iron-doped molybdenum carbide is designed and fabricated for the first time as an efficient OER catalyst due to improved reactant adsorption. The Fe-Mo₂C@CN catalyst exhibits excellent OER activity, requiring an overpotential of 223 mV to achieve a current density of 10 mA cm⁻². Simultaneously, Fe-Mo₂C@CN demonstrates a water electrolysis potential of 2.13 V at 1000 mA cm⁻² and maintains full hydrolytic stability under OER and industrial conditions: it operates for 240 h at 200 mA cm⁻² and 100 h at 1000 mA cm⁻² with minimal performance degradation. XPS results reveal that the introduction of Fe optimizes the electronic structure around Mo₂C. Methanol probe experiments show that Fe incorporation enhances the adsorption of OH* on the catalyst surface, thereby improving OER catalytic performance. In-situ Raman experiments indicate that Fe may act as a new active site (FeOOH) to catalyze the reaction, further enhancing catalyst performance. Additionally, theoretical calculations and kinetic simulations demonstrate that Fe improves OH⁻ adsorption by the catalyst, increasing the concentration of OER reactants on Fe-Mo₂C@CN and accelerating the OER process.