Enhancing hydrogen peroxide electrosynthesis by manipulating the three-phase interface microenvironment

Oxygen reduction reaction through the two-electron pathway holds promise for on-site hydrogen peroxide production; however, achieving high activity without compromising selectivity remains a long-standing challenge in catalyst design. Herein, we overcome this challenge by engineering a solid-liquid-gas three-phase inter-face that creates a hydrophobic microenvironment to enhance interfacial mass and electron transfer while retaining active sites. The engineered vertical graphene electrode exhibits greater than 97% Faradaic efficiency in alkaline media and greater than 90% Faradaic efficiency in neutral media, both at a large potential window (0.7-1.0 V). Continuous hydrogen peroxide production at 1,200 mg L-1 h-1 is achieved in a flow cell with neutral medium utilizing the engineered electrode. Kelvin probe force microscopy and in situ Raman spectroscopy reveal that graphene step edges possess a low work function that promotes two-electron reaction kinetics, while ab initio molecular dynamics show that the hydrophobic three-phase interface microenvironment balances the contact of graphene edges, oxygen, and water.