Design and construction of a Ag3PO4 NPs/protonated g-C3N4 nanosheet S-scheme heterojunction for photocatalytic degradation of C2H4

The removal of ethylene (C2H4) from storage environments is essential for extending the shelf life of fruits and vegetables. However, achieving efficient catalytic degradation of C2H4 under visible-light irradiation remains a crucial challenge. Distinct from other approaches, the S-scheme heterojunction offers a unique strategy for the successful separation of photogenerated charge carriers while preserving robust redox active sites. Our density functional theory (DFT) computations, indicated an S-scheme heterojunction is expected to develop between Ag3PO4 and g-C3N4. By protonating g-C3N4 nanosheets to create rich functional groups and good dispersion, an S-scheme Ag3PO4 nanoparticles (NPs)/protonated g-C3N4 nanosheet composite was studied under simulated sunlight and visible-light irradiation. The space charge transfer pathways of Ag3PO4 NPs and g-C3N4 were analyzed, using UV–Vis DRS, UPS, in situ irradiated XPS and ESR, and the successful formation of the S-scheme heterojunction was confirmed. The results show that the unique structural design can effectively improve the stability of the catalyst, while achieving efficient charge transfer and sufficient redox capacity. The photocatalytic degradation rate of Ag3PO4 NPs/protonated g-C3N4 nanosheet heterojunction is 3.31 × 10−2∙min−1, 11.3 times higher than that of Ag3PO4 and 99.1 times higher than g-C3N4. This research advances the exploration of technologies aimed at removing C2H4 from air and improving the stability of photocorrosive substances such as Ag3PO4.