Mesoporous Carbon Hollow Spheres as Efficient Electrocatalysts for Oxygen Reduction to Hydrogen Peroxide in Neutral Electrolytes

Hydrogen peroxide is a widely used and important chemical in industry. A two-electron electrochemical oxygen reduction reaction (2e(-) ORR) is a clean and on-site method for H2O2 production. Here, we report metal-free catalysts (mesoporous carbon hollow spheres, MCHS) for high-efficiency H2O2 production in neutral electrolytes (0.1 M PBS). The selectivity of H2O2 on MCHS catalysts is higher than 90% at a wide range of potentials (0.35-0.62 V), and it can reach 99.9% at a potential of 0.57 V. These catalysts show some of the best performances for H2O2 production in neutral electrolytes. It is preferable to develop H2O2 catalysts in a neutral environment, as the pH of the stabilizers used for H2O2 is also close to neutral. The outstanding activity of our catalyst comes from a combination of factors such as suitable porosity, the content of oxygen functional groups, and the types of different species of oxygen functional groups. First-principles simulations show that a catalyst with suitable mixed oxygen and COOH functional groups plays an important role in the catalytic formation of H2O2. The reported metal-free catalysts are promising catalysts for high-efficiency production of H2O2 in the future.