Selective Electrochemical Generation of Hydrogen Peroxide from Oxygen Reduction on Atomically Dispersed Platinum

A catalyst with an atomically dispersed metal center may provide an ideal structure for the electrochemical synthesis of H2O2 due to the distinct chemoselectivity. Herein, we report a simple electrochemical method to prepare atomically dispersed Pt catalyst on a sulfur-doped carbon structure (Pt1-meso-S-C) by underpotential deposition (UPD) of copper atoms followed by a galvanic replacement reaction under ambient conditions. Sulfur doping in the carbon structure shows a strong affinity to metal atoms, resulting in underpotential deposition (UPD) of a single copper adatom at a potential positive to its thermodynamic equilibrium potential. Galvanic replacement of the UPD Cu by platinum precursor leads to the formation of a single-atom Pt catalyst on a sulfur-doped carbon structure. This Pt1-meso-S-C acts as a highly selective catalyst for the electrochemical reduction of O2 into H2O2 without promoting consecutive H2O2 decomposition. However, the catalysts (Ptn-meso-S-C and Pt/C) with the platinum ensemble sites exhibit a four-electron pathway for oxygen reduction reaction (ORR) and the consecutive H2O2 decomposition. This work demonstrates that the reaction mechanism can be adjusted by the dispersion of metal catalysts.