High Spatial Resolution Electrochemical Microscopic Observation of Enhanced Charging under Bias at Active Sites of N-rGO

Recent breakthrough reveals that the activation free energy decreases with the amount of the oxidative charge stored at the catalyst, which gives an insight into the role of chemistry vs bias in electrocatalysis. In this study, non-faradic and faradic currents from the total currents in the image of scanning electrochemical cell microscopy (SECCM) are isolated to realize the mapping of charge accumulation and electrochemical activity with a resolution of ∼135 nm. Enhanced charging under bias is observed at the active sites of N-doped graphene oxide (N-rGO) with high electrochemical activity in the hydrogen evolution reaction (HER), providing direct evidence to support the mechanism as mentioned above. This established electrochemical imaging method and the collected result could provide more effective information about the electrochemical mechanism of the HER performance, which is significant for the design of high HER catalysts.