Solid-Solution-Like o-C3N4/Ag2SO4 Nanocomposite as a Direct Z-Scheme Photocatalytic System for Photosynthesis of Active Oxygen Species

Efficient photosynthesis of active oxygen species (e.g., •OH, •O 2 –, and H 2 O 2 ) is of cardinal significance for environmental science and biochemistry. We report a system of o -C 3 N 4 /Ag 2 SO 4 with solid-solution-like structure synthesized by coordinating the 5s orbit of Ag + with surface 2p lone electrons of o -C 3 N 4 . The as-synthesized o -C 3 N 4 /Ag 2 SO 4 demonstrates a unique electronic structure, as illuminated high light absorption, perfect redox potentials, large BET specific area, abundant active sites, and efficient interfacial charge transfer. Electron paramagnetic resonance spectra and Mott–Schottky measurements confirm that o -C 3 N 4 /Ag 2 SO 4 photocatalysts demonstrate highly efficient activity for yielding •OH, •O 2 –, and H 2 O 2 species with the Z-scheme photocatalytic principle. Experimental and DFT calculation reveal that the transferred electrons on the conduction band (CB) made up of Ag 5s were favorably shifted into the valence band (VB) composed of N 2p with the formed coordination under irradiation, greatly promoting electron transportation in the Z-scheme photocatalytic system. ( o -C 3 N 4 ) 2 /(Ag 2 SO 4 ) 1 with the mass ratio of 2 to 1 possesses the highest photocatalytic rate of •OH (45 μmol L –1 h –1 ), •O 2 – (87 μmol L –1 h –1 ), and H 2 O 2 (480 μmol L –1 h –1 ). The work provides a new approach to design advanced photocatalysts to efficiently yield active oxygen species for environmental purification.