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

Authors：He, Liuqing; Zhang, Wenbiao; Mo, Qijie; Huang, Wenjie; Yang, Lichun^*; Gao, Qingsheng^*

Source：Angewandte Chemie - International Edition, 2020, 59(9): 3544-3548.

DOI：10.1002/anie.201914752

• heterointerfaces
• hydrogen evolution reaction
• in situ reconfiguration
• molybdenum carbides
• surface oxides

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.