Phosphorus and Oxygen Co-doping Inducing Surface Defects of Carbon Nanospheres to Enhance the Catalytic Performance for Two-Electron Oxygen Reduction Reaction

Electrochemical oxygen reduction reaction (ORR) is a promising alternative to the conventional anthraquinone oxidation process, with high energy consumption and massive pollutant discharge, for hydrogen peroxide (H2O2) production. However, improving the selectivity of two-electron (2e(-)) ORR toward H2O2 remains a large challenge. Here, a simple and scalable P, O-codoped strategy is proposed to improve the catalytic activity and H2O2 selectivity of the low-cost carbon nanospheres (P-O-CNS). The optimal O and P contents and abundant defects make P-O-CNS-800 obtain the highest selectivity for H2O2 (95.47% at 0.580 V vs RHE), greatly superior to those of the initial O-CNS (75.74%) and other P-O-CNS samples with low doping content. The theoretical investigation further reveals the synergistic effect of doped P and defect structures optimizing the adsorption of *OOH on the active sites near the oxygen-containing functional group as the reason for the enhanced 2e(-) ORR catalytic activity. This study offers comprehensive insight into the regulating mechanism of the carbon structures with multiheteroatom doping for improved ORR activity as well as H2O2 selectivity and then provides more possibilities for the rational regulation of catalysts to obtain a high-efficiency catalytic performance.