Deciphering Anion-Induced Dynamic Heterogeneity of Electrochemiluminescence on Single Gold Microplates via...

Electrochemiluminescence (ECL) microscopy has been widely used for visualization of electrochemical heterogeneity. Nevertheless, given the intricate nature of ECL reaction mechanisms, directly correlating the observed luminescence distribution with the material's intrinsic catalytic activity is open to interpretation. In this work, the origin of Ru-(bpy)₃ ²⁺/DBAE ECL heterogeneity on single Au microplates is investigated by in situ multiresolved ECL imaging/visible absorption imaging. The results demonstrate that the suppressed ECL activity on basal planes arises from the sluggish electrocatalytic kinetics of the coreactant DBAE. Specifically, visible absorption imaging reveals a dense accumulation of DBAE oxidation products on the basal planes, indicating kinetic stagnation and slow desorption that restrict the flux of radical intermediates required for emission. To overcome this "adsorption-induced inhibition", a strategy involving anion-regulated interfacial reconstruction is introduced. The specific adsorption of sulfate anions forms a structural scaffold within the electric double layer that physically disrupts the dense accumulation of DBAE oxidation products. This reconstruction supersedes the intrinsic facet-dependence of the gold surface, establishing a uniform kinetic environment that homogenizes ECL emission across the entire microplate. These findings underscore the critical role of coreactant kinetics in governing ECL heterogeneity and, furthermore, provide a mechanistic foundation for tailoring electrocatalysis via rational electrolyte design.