In-situ phase transition of WO3 boosting electron and hydrogen transfer for enhancing hydrogen evolution on Pt

Pt/WO3 catalysts have been reported to possess excellent HER activity closing to commercial Pt/C, however, the promoting mechanism of WO3 in enhancing HER activity has not been clarified. Herein, we have successfully prepared a series of Pt-WO3 catalysts with outstanding HER performance and low Pt contents by a simple method. Via in-situ Raman spectroscopy and electrochemical impedance spectroscopy characterization, the electrochemically driven in-situ phase transition from WO3 to HxWO3 was identified and the significant role of HxWO3 in promoting electron transfer during HER process and accelerating HER kinetics by providing the hydrogen transfer pathway from HxWO3 onto Pt have been revealed. This work emphasized the importance of tracking the catalyst structure dynamic evolution and provided a deep insight into the electron/hydrogen transfer process for electrocatalytic HER.