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.