Molecule Confined Isolated Metal Sites Enable the Electrocatalytic Synthesis of Hydrogen Peroxide

The direct synthesis of hydrogen peroxide (H2O2) through the two-electron oxygen reduction reaction is a promising alternative to the industrial anthraquinone oxidation process. Selectivity to H2O2 is however limited by the four-electron pathway during oxygen reduction. Herein, it is reported that aminoanthraquinone confined isolated metal sites on carbon supports selectively steer oxygen reduction to H2O2 through the two-electron pathway. Confining isolated NiNx sites under aminoanthraquinone increases the selectivity to H2O2 from below 55% to above 80% over a wide potential range. Spectroscopy characterization and density functional theory calculations indicate that isolated NiNx sites are confined within a nanochannel formed between the molecule and the carbon support. The confinement reduces the thermodynamic barrier for OOH* desorption versus further dissociation, thus increasing the selectivity to H2O2. It is revealed how tailoring noncovalent interactions beyond the binding site can empower electrocatalysts for the direct synthesis of H2O2 through oxygen reduction.