Aerogel is introduced as an OER catalyst substrate for PEM electrolyzer and shows superior activity.

The abundance of available surface chemical information and edge structures of carbon materials have attracted tremendous interest in catalysis. For the oxygen evolution reaction (OER), the edge effects of carbon materials have rarely been studied in detail because of the complexity of various coexisting edge configurations and the controversy between carbon corrosion and carbon catalysis. Herein, the exact roles of common carbon active edge sites in the OER were interrogated using polycyclic aromatic hydrocarbons (PAHs) with designated configurations (zigzag and armchair) as model probe molecules, with a focus on structure–function relationships. Zigzag configurations of PAHs showed high activity for the OER while also showing a good stability at a reasonable potential. They show a TOF value of 0.276 s −1 in 0.1 m KOH. The catalytic activity of carbon edge sites was further effectively regulated by extending the π conjugation structure at a molecular level.

The recent mechanistic understanding of active sites, adsorbed intermediate products, and rate‐determining steps (RDS) of nitrogen (N)‐modified carbon catalysts in electrocatalytic oxygen reduction (ORR) and oxygen evolution reaction (OER) are still rife with controversy because of the inevitable coexistence of diverse N configurations and the technical limitations for the observation of formed intermediates. Herein, seven kinds of aromatic molecules with designated single N species are used as model structures to investigate the explicit role of each common N group in both ORR and OER. Specifically, dynamic evolution of active sites and key adsorbed intermediate products including O2 (ads), superoxide anion O2−*, and OOH* are monitored with in situ spectroscopy. We propose that the formation of *OOH species from O2−* (O2−*+H2O→OOH*+OH−) is a possible RDS during the ORR process, whereas the generation of O2 from OOH* species is the most likely RDS during the OER process.