Molybdenum Carbide-Oxide Heterostructures: In Situ Surface Reconfiguration toward Efficient Electrocatalytic Hydrogen Evolution

摘要

Heterostructured Mo2C-MoOx on carbon cloth (Mo2C-MoOx/CC), as a model of easily oxidized electrocatalysts under ambient conditions, is investigated to uncover surface reconfiguration during the hydrogen evolution reaction (HER). Raman spectroscopy combined with electrochemical tests demonstrates that the Mo-VI oxides on the surface are in situ reduced to Mo-IV, accomplishing promoted HER in acidic condition. As indicated by density functional theoretical calculations, the in situ reduced surface with terminal Mo=O moieties can effectively bring the negative Delta G(H*) on bare Mo2C close to a thermodynamic neutral value, addressing difficult H* desorption toward fast HER kinetics. The optimized Mo2C-MoOx/CC only requires a low overpotential (eta(10)) of 60 mV at -10 mA cm(-2) in 1.0 m HClO4, outperforming Mo2C/CC and most non-precious electrocatalysts. In situ surface reconfiguration are shown on W2C-WOx, highlighting the significance to boost various metal-carbides and to identify active sites.

关键词