Visible light-driven aerobic oxidation of amines coupling with H₂O₂ production catalyzed by CoPc/alkali metal-doped g-C₃N₄ Z-scheme heterojunction

Three environmentally friendly Z-scheme CoPc/alkali metal-doped g-C₃N₄ heterojunction composites were fabricated via in-situ immobilizing cobalt phthalocyanine (CoPc) on the surface of alkali metal-doped g-C₃N₄ nanosheet by simple hydrothermal method. These composites acted as efficient and recyclable heterogeneous photocatalysts realized that the highly selective aerobic oxidation of amines to the corresponding imines coupling of hydrogen peroxide generation at room temperature. Under irradiation by LED lamp, the imines and H₂O₂ were obtained with conversion ranges from 87.9 % to 92.0 %, selectivity more than 99 %, and production rate ranges from 3.27 to 3.40 mmol g⁻¹ h⁻¹, respectively. Based on the mechanistic analysis and characterization, the excellent catalytic activity derived from the Z-scheme mechanic and synergistic effect originated from O₂ reduction and amine oxidation. On completion, after centrifugation, washing with solvent and drying under vacuum, the catalysts can be recovered and reused for five successive cycles of testing with a slight decrease in reactivity. For this work, a promising photo synthesis pathway with merits of mild, low-cost, pollution-free, and energy-saving was developed to produce imines coupling with H₂O₂ generation.