Construction of g-C3N4 nanotube/Ag3PO4 S-scheme heterojunction for enhanced photocatalytic oxygen generation

Heterojunction engineering is considered as a hopeful approach to ameliorate the separation of photogenerated carriers of photocatalysts, realizing efficient water-splitting performance. In this study, an organic-inorganic S-scheme of a one-dimensional g-C3N4 nanotube (TCN)/Ag3PO4 photocatalytic system with high photocatalytic water oxidation activity was designed by coupling g-C3N4 nanotubes over Ag3PO4 particles through a chemical coprecipitation method. The TCN/Ag3PO4 heterojunction demonstrated excellent photocatalytic O2 production with an O2 evolution rate of up to 370.2 μmol·L−1·h−1. X-ray photoelectron spectroscopy analysis showed that electron migration between TCN and Ag3PO4 led to the formation of an internal electric field pointing from TCN to Ag3PO4, which drove the S-scheme charge transfer mode between TCN and Ag3PO4. Accordingly, the TCN/Ag3PO4 heterojunction possessed fast charge separation and high redox ability, leading to high photoactivity and photostability. This research provides a new strategy for fabricating highly efficient inorganic-organic S-scheme photocatalysts for O2 production.