Operando Insight into the Oxygen Evolution Kinetics on the Metal-Free Carbon-Based Electrocatalyst in an Acidic Solution

Operando insight into the catalytic kinetics under working conditions is important for further rationalizing the design of advanced catalysts toward efficient renewable energy applications. Here, we enable a ubiquitous carbon material as an efficient acidic oxygen evolution reaction (OER) electrocatalyst, synthesized via a facile and controllable "amino-assisted polymerization and carbonization" strategy. This as-developed metal-free amino-rich hierarchical-network carbon (amino-HNC) framework directly supported on carbon paper can catalyze OER at a quite low overpotential of 281 mV and a small Tafel slope of 96 mV dec^-1 in an acid solution, and maintain ∼98% of its initial catalytic activity after 100 h oxygen evolution operation. By using the operando synchrotron infrared spectroscopy, a crucial structurally evolved H₂N-(*O-C)-C, formed by adsorbing the *O intermediate on the active H₂N-C═C moiety, is observed on amino-HNC electrocatalysts during the OER process in the acid medium. Furthermore, theoretical calculations reveal that the optimization of the sp² electronic structure of C═C by amino radicals could effectively lower the kinetic formation barrier of the *O intermediate on the H₂N-C═C moiety, contributing to a prominent acidic oxygen-involved catalysis.