Cost effective Mo rich Mo₂C electrocatalysts for the hydrogen evolution reaction

Cost-effective electrocatalysts for the hydrogen evolution reaction (HER) are attractive for energy conversion and storage processes. Despite high efficiency for the HER, noble metal electrocatalysts are not cost-effective for hydrogen production due to their high cost and low abundance. This paper reports a new and efficient non-noble HER electrocatalyst based on molybdenum rich Mo₂C (Mo–Mo₂C). The results show that the onset overpotential of Mo–Mo₂C is only 67 mV and its Tafel slope is as low as 55 mV dec⁻¹. To obtain a 10 mA cm⁻² cathodic current density, the Mo–Mo₂C catalyst requires only a 150 mV overpotential. In an acidic electrolyte, the Mo–Mo₂C catalyst can achieve 0.019 mA cm⁻² exchange current density. The electrocatalyst also demonstrates an excellent long-term durability of more than 12 hours at a current density of 20 mA cm⁻². Characterization of the Mo–Mo₂C catalyst indicates that its superior HER activities can be attributed to the electrode conductivity improvement for the charge transfer. This study shows that molybdenum rich Mo₂C is potentially a highly active non-noble metal electrocatalyst for hydrogen production via water electrolysis.