Synthesis and Characterization of Mo2C/MoO3 Nanohybrid as Electrocatalyst for Hydrogen Evolution Reaction

The two-step preparation of core-shell Mo2C/MoO3 nanoplatelets (composed of an MoO3 core covered by 3 nm Mo2C outer layer) is reported. The process consists of the thermolysis of a solid precursor, ammonium molybdate ((NH4)6Mo7O24•·4H2O), in a reactor fed by nitrogen (200 cm3(STP)/min), heated from room temperature to 700 °C, followed by a controlled Chemical Vapor Deposition (CVD) of CH4, 10 v/v % innitrogen, for 10 minutes, monitored on-line by continuous gas analyzers. A Tafel slope of 48 mV/decade was measured for the Mo2C/MoO3 nanohybrid suggesting the Volmer- Heyrovsky mechanism for the nanohybrid-catalyzed HER. MoO3 deserves as a highly nanostructured conductive core, while the thin Mo2C coating serves as both a HER catalyst and a protective layer.