EFFECTIVE ELECTROCATALYST FOR HYDROGEN EVOLUTION FROM WATER BASED ON VANADIUM DOPED Mo2C, Mo2N AND REDUCED GRAPHENE OXIDE

Abstract

Molybdenum compounds (Mo2C, MoS2, MoP, Mo2N, etc.) and their composites with different nanosized carbon materials are considered to be one of the most promising Pt-free hydrogen evolution reaction (HER) electrocatalysts. Along with non-metallic dopants (N, P etc.), d-metals are also used as dopants to increase the activity of Mo-containing hybrid catalysts in HER. Thus, we have recently shown the possibility of obtaining HER nanocomposite electrocatalysts based on vanadium doped particles of Mo2C and N,P-doped reduced graphene oxide (rGO) using precursor based on polypyrrole, H3PVMo11O40 (PVMo11) and rGO – V-Mo2C/N,P-rGO. It was found that doping with vanadium atoms in situ promotes an increase in the activity of catalysts in HER, compared with the analogue obtained in the absence of V doping. The nature of the nitrogen-containing conjugated polymer can also affect the type of metal-containing particles formed during the high-temperature processing of such macromolecules together with the metal precursors. Given this, the paper shows the possibility of obtaining a promising hybrid electrocatalyst for HER based on vanadium-doped Mo2C, Mo2N and N,P-doped rGO (V-Mo2C,Mo2N/N,P-rGO) by pyrolysis of composite-precursor based on poly-5-aminoindole, PVMo11 and rGO. It was found that the simultaneous presence of Mo2C and Mo2N phases in the catalyst causes an increase in the activity of V-Mo2C,Mo2N/N,P-rGO in HER compared to the analogue containing only Mo2C phase (V-Mo2C/N,P-rGO), which is manifested in reduction in hydrogen evolution overpotential at a current density of 10 mA/cm2 (on 15-29 mV), an increase in the magnitude of exchange currents (by ~ 2.3-2.7 times), as well as in the anodic shift of the process onset potential and the reduction of Tafel slope (in alkaline electrolyte).