Sunlight‐Driven Hydrogen Peroxide Production from Water and Molecular Oxygen by Metal‐Free Photocatalysts

Abstract

Design of green, safe, and sustainable process for the synthesis of hydrogen peroxide (H₂O₂) is a very important subject. Early reported processes, however, require hydrogen (H₂) and palladium-based catalysts. Herein we propose a photocatalytic process for H₂O₂ synthesis driven by metal-free catalysts with earth-abundant water and molecular oxygen (O₂) as resources under sunlight irradiation (λ>400 nm). We use graphitic carbon nitride (g-C₃N₄) containing electron-deficient aromatic diimide units as catalysts. Incorporating the diimide units positively shifts the valence-band potential of the catalysts, while maintaining sufficient conduction-band potential for O₂ reduction. Visible light irradiation of the catalysts in pure water with O₂ successfully produces H₂O₂ by oxidation of water by the photoformed valence-band holes and selective two-electron reduction of O₂ by the conduction band electrons.