Promoting the Two-Electron Oxygen Reduction Reaction Performance of Carbon Nanospheres by Pore Engineering

Electrochemical production of hydrogen peroxide from the two-electron oxygen reduction reaction (ORR) is emerging as a promising method for in situ production of H2O2. However, carbon materials, one of the most prospective catalysts for the two-electron ORR, remain not active enough for mass production of H2O2 in acidic or neutral media. Pore channel engineering is an effective strategy to enhance the ORR activity of carbon materials by enlarging the electrochemically accessible surface and facilitating oxygen diffusion. Here, carbon nanospheres with different pore sizes (diameter and depth) were controllably prepared by a soft-template method. The optimized catalyst exhibited an excellent two-electron ORR activity in alkaline and neutral media. Furthermore, electrochemical production of H2O2 in neutral solution with a production rate as high as 1.27 mol g–1 h–1 and a Faraday's efficiency (FE) > 98% were obtained. By combining electrochemical tests with physical characterizations and numerical simulations, the origin of the enhanced ORR performances was elucidated.