Fluorine-regulated carbon nanotubes decorated with Co single atoms for multi-site electrocatalysis toward two-electron oxygen reduction

Producing hydrogen peroxide (H2O2) via a two-electron oxygen reduction reaction (2 e(-)-ORR) is a promising alternative to the conventional anthraquinone process, because of its exceptional low-risk and distributed features. The low yield of H2O2 on typical electrocatalysts, usually associated with limited and vulnerable catalytically active sites on their surface, has been the major restriction for improving the practical viability of this technology. Herein, we report an ultrafast microwave-based strategy for constructing distant coordination of Co single-atom sites with secondary fluorene heterodopants on carbon nanotubes, which successfully converts the 2 e(-)-ORR active centers from a single Co atom to multiple surrounding carbon atoms, increasing both the quantity and durability of active sites for 2 e(-)-ORR. Consequently, a high H2O2 yield of up to 18.6 mol g(-1) L-1 has been achieved, accompanied by a Faraday efficiency of 90%. Besides, an accumulative H2O2 concentration of 5.2 g L-1 is obtained after 20 h electrocatalysis, showing the material's high stability and feasibility for practical applications. Density functional theory simulations confirm the optimal adsorption of *OOH on these carbon sites, providing very low kinetic barriers for 2 e(-)-ORR. Thus, this work provides a high-performance electrocatalyst for 2 e(-)-ORR, and more importantly strategy for promoting the performance of single-atom catalysts.