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.
Keywords: Fourier-transform infrared spectroscopy; amino-rich carbon framework; metal-free electrocatalyst; operando technique; oxygen evolution reaction.