Synthesis of iron-doped molybdenum carbide via gas–solid reaction as an electrocatalyst for the oxygen evolution reaction

Santos N.M.; Lima M.J.S.; Raimundo R.A.; Checca R.; Mastelaro V.R.; Gomes U.U.; Morales M.A. · Journal of Alloys and Compounds (2026) · DOI: 10.1016/j.jallcom.2026.189043

Resumen

The development of efficient, low-cost electrocatalysts as alternatives to RuO₂/IrO₂-based systems for the oxygen evolution reaction (OER) remains challenging, primarily due to the slow reaction kinetics, the need for high activity and stability, and the high cost and low abundance of noble metals. In this study, pure Mo₂C electrocatalysts and iron-doped Mo₂C electrocatalysts (1, 3, and 5 wt%) were synthesized via a gas-solid reaction using H₂/CH₄ as the reaction atmosphere, starting from ammonium heptamolybdate and iron nitrate, followed by heat treatment at 700 °C for 2 h. X-ray diffraction analysis revealed a single-phase Mo₂C in the samples containing 0, 1 and 3% Fe, whereas the sample with 5% Fe contained mainly Mo₂C and a small amount of metallic iron (α-Fe), as confirmed by Mössbauer spectroscopy. SEM analyses indicated particles with irregular morphology and a heterogeneous size distribution. XPS confirmed the presence of Mo, Fe, C, and O, having Mo and Fe several oxidation states. The Raman spectra revealed the presence of the β-Mo₂C phase. In electrocatalytic tests conducted in an alkaline medium, increasing the Fe concentration increased the overpotential reduced from 346 mV to 268 mV at 20 mA cm⁻² and significantly decreased the charge-transfer resistance from 21.0 to 1.9 Ω cm−2. The catalysts also exhibited stability for 24 h. These outcomes indicate that the incorporation of Fe into Mo₂C improves electrocatalytic activity and makes the material promising for OER.

Instituciones: Universidad Nacional de Ingeniería