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

Abstract

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 (H 2 O 2 ) production. However, improving the selectivity of two-electron (2e − ) ORR toward H 2 O 2 remains a large challenge. Here, a simple and scalable P, O-codoped strategy is proposed to improve the catalytic activity and H 2 O 2 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 H 2 O 2 (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 H 2 O 2 selectivity and then provides more possibilities for the rational regulation of catalysts to obtain a high-efficiency catalytic performance.