Black Phosphorous Mediates Surface Charge Redistribution of CoSe2 for Electrochemical H2O2 Production in Acidic Electrolytes

Electrochemical generation of hydrogen peroxide (H2O2) by two-electron oxygen reduction offers a green method to mitigate current dependence on the energy-intensive anthraquinone process, promising its on-site applications. Unfortunately, in alkaline environments, H2O2 is not stable and undergoes rapid decomposition. Making H2O2 in acidic electrolytes can prevent its decomposition, but choices of active, stable and selective electrocatalysts are significantly limited. Here we report the selective and efficient two-electron reduction of oxygen towards H2O2 in acid by a composite catalyst that composed of black phosphorus (BP) nailed chemically on the metallic cobalt diselenide (CoSe2) surface. We find that this catalyst exhibits a 91% Faradic efficiency for H2O2 product at an overpotential of 300 millivolts. Moreover, it can mediate O2 to H2O2 with a high production rate of ca. 1530 mg L-1 h-1 cm-2 in a flow cell reactor. Spectroscopic and computational studies together uncover a BP-induced surface charge redistribution in CoSe2, which leads to a favorable surface electronic structure that weakens the HOO* adsorption, thus enhancing the kinetics towards H2O2 formation. This article is protected by copyright. All rights reserved.