KOH-Assisted Band Engineering of Polymeric Carbon Nitride for Visible Light Photocatalytic Oxygen Reduction to Hydrogen Peroxide

Visible light-driven photocatalytic production of H2O2 from molecular oxygen represents a promising route to transform solar energy to green oxidants and solar fuels. Herein, KOH-assisted thermal polymerization of urea was adopted to controllably incorporate cyano groups into the polymeric carbon nitride (PCN) framework. Photoelectrical techniques and density functional theory (DFT) calculations disclosed that the cyano groups effectively narrow down the band gap, elevate the conduction band, and improve the generation, transmission, and lifetime of the photoexcited charge carriers, which synergistically boost the H2O2 productivity by up to 5.4 times with respect to that on the pristine PCN in photocatalytic reduction of molecular oxygen under visible light at room temperature. This facile and effective strategy to enhance the photocatalytic activity of the inexpensive PCN catalyst under visible light enriches the horizon of H2O2 production in an economic, safe, and environmentally benign manner.