Revealing Kinetics of Two-Electron Oxygen Reduction Reaction at Single-Molecule Level

By combining single-molecule fluorescence microscopy with traditional electrochemical methods, herein we report on the investigation of the electrocatalytic kinetics of two-electron (2e) pathway of oxygen reduction reaction (ORR) on a single Fe₃O₄ nanoparticle. The kinetic parameters for two-electron ORR process are successfully derived at the single-particle level, and a potential dependence of dynamic heterogeneity among individual nanoparticles is revealed. Furthermore, the performance stability of individual Fe₃O₄ nanoparticles for 2e ORR process is studied. This study deepens our understanding to the electrocatalytic ORR process, especially the 2e pathway at single-molecule and single-particle levels.