One-pot synthesis of potassium and phosphorus-doped carbon nitride catalyst derived from urea for highly efficient visible light-driven hydrogen peroxide production

Abstract

Photocatalytic production of hydrogen peroxide (H2O2) from two-electron reduction of molecular oxygen over semiconductor catalysts under visible light irradiation represents a clean and sustainable strategy to transform solar energy to chemicals. Here we synthesized a series of potassium and/or phosphorus-doped carbon nitride photocatalysts by one-pot thermal polymerization of urea and different sylvites and phosphates. Among them, the K2HPO4/GCN (CNKP-10) catalyst exhibited the best visible light photocatalytic activity for H2O2 production from molecular oxygen. After 10 h visible light (λ ≥ 420 nm) irradiation, the concentration of H2O2 exceeded 5 mmol l–1 on this catalyst, which is more than five folds of that on the catalyst synthesized by thermal polymerization of urea only (GCN). A combination of bulk and surface characterization techniques confirmed the incorporation of potassium and phosphorus into the framework of GCN, which narrowed down the band gap, raised the conduction band, and enhanced the generation, transmission, and lifetime of the photogenerated charge carriers, thus promoting the visible light photocatalytic production of H2O2 from molecular oxygen.