Molybdenum Carbide‐Decorated Metallic Cobalt@Nitrogen‐Doped Carbon Polyhedrons for Enhanced Electrocatalytic Hydrogen Evolution

: Electrocatalytic hydrogen evolution reaction (HER) based on water splitting holds great promise for clean energy technologies, in which the key issue is exploring cost-effective materials to replace noble metal catalysts. Here, a sequential chemical etching and pyrolysis strategy are developed to prepare molybdenum carbide-decorated metallic cobalt@nitrogen-doped porous carbon polyhedrons (denoted as Mo/Co@N-C) hybrids for enhanced electrocatalytic hydrogen evolution. The obtained metallic Co nanoparticles are coated by N-doped carbon thin layers while the formed molybdenum carbide nanoparticles are well-dispersed in the whole Co@N-C frames. Benefiting from the additionally implanted molybdenum carbide active sites, the HER performance of Mo/Co@N-C hybrids is significantly promoted compared with the single Co@N-C that is derived from the pristine ZIF-67 both in alkaline and acidic media. As a result, the as-synthesized Mo/Co@N-C hybrids exhibit superior HER electrocatalytic activity, and only very low overpotentials of 157 and 187 mV are needed at 10 mA cm-2 in 1 m KOH and 0.5 m H2 SO4 , respectively, opening a door for rational design and fabrication of novel low-cost electrocatalysts with hierarchical structures toward electrochemical energy storage and conversion.