Copper/Carbon Nanocomposites for Electrocatalytic Reduction of Oxygen to Hydrogen Peroxide

Electrocatalytic synthesis of hydrogen peroxide (H2O2) via two-electron reduction of oxygen has emerged as an effective strategy to replace the traditional anthraquinone oxidation route. Herein, copper/carbon nanocomposites are prepared by pyrolytic treatment of a metal organic framework precursor, which consists of copper oxide (CuOx) nanoparticles dispersed within a carbon matrix, as evidenced by results from transmission electron microscopy and X-ray photoelectron spectroscopy measurements. Deliberate electrochemical activation enriches the Cu2O species on the nanocomposite surface and markedly enhances the performance of electrocatalytic oxygen reduction to H2O2 with the selectivity increased to 68% from ca. 45% (at +0.1 V) for the as-produced counterparts. This can be exploited for the effective electrochemical degradation of methylene blue. This is accounted for by the weakened interaction with peroxide intermediates on Cu2O, as confirmed by results from first-principles calculations. Results from this study underline the significance of structural engineering based on electrochemical activation for the enhanced selectivity of oxygen reduction reaction for H2O2 production.