Facile synthesis of molybdenum carbide interspersed in biomass-derived N-doped carbon matrix for efficient hydrogen evolution reaction

It is essential to develop highly active and robust electrocatalysts for the hydrogen evolution reaction (HER) to address the issue of sustainable energy with hydrogen as a renewable energy source. Molybdenum carbide (Mo2C) has been regarded as a promising substitute for noble metal catalysts during the HER process. However, the limited number of exposed active sites and strong Mo-H binding energy of Mo2C seriously hinder the catalytic application to produce hydrogen. Herein, the most abundant marine polysaccharide chitin, was used as carbon and nitrogen sources to fabricate molybdenum carbide particles embedded in a nitrogen-doped carbon matrix (Mo2C@NC). The morphology of the produced molybdenum carbide could be tailored with different amounts of hydrogen chloride (HCl) used during the synthesis. The optimized Mo2C@NC shows good electrocatalytic performance and stability in an acidic medium with an overpotential of 168 mV to reach 10 mA cm-2 and a Tafel slope of 62.68 mV dec-1. The improved performance is chiefly attributed to a relatively large specific surface area of the hybrid catalyst, carbonaceous support preventing particle aggregation, and nitrogen in both the carbon framework and Mo2C, which reduces the desorption energy of Mo-H bonds.