Radical Cation Lifetime Regulating Anomalous Signal Fluctuation on Au(111) Unveiled by Electrochemiluminescence Microscopy

The electrocatalytic activity of metals is intrinsically governed by their surface chemical states, which, however, often degrades due to surface oxidation during electrocatalysis. Thus, enhancing oxidation resistance to improve the catalytic performance of metal materials is a pivotal challenge. Herein, we report a strategy to revive the catalytic activity of oxidized Au(111) facets via chemical reduction by highly reductive radicals in situ generated during electrocatalysis. Using electrochemiluminescence microscopy (ECLM), we achieved the real-time visualization of an anomalous signal fluctuation on Au(111) facets during ECL reactions, which arises from the continuous surface redox dynamics. In conjunction with electrochemiluminescence self-interference spectroscopy (ECLIS) and finite element simulations, we reveal that the lifetime of co-reactant radical cations strongly modulates the reduction kinetics of Au surface oxides and that the localized Au oxide reduction is governed by the surface distribution of co-reactant radicals. For the first time, we capture the ECLM-based real-time images of the surface redox processes on Au(111) facets during electrocatalysis with a temporal resolution of 100 ms. This work underscores the potential of ECLM for in situ monitoring of electrocatalytic reactions and establishes a new strategy for reviving the catalytic activity of Au(111) using reaction-derived highly reductive radicals.