Synergistic Effects of Internal Electric and Dipole Fields in SnNb2O6/Nitrogen-Enriched C3N5 S-Scheme Heterojunction for Boosting Photocatalytic Performance

Directional electron transfer is an appealing strategy for harnessing photogenerated charge separation kinetics. Herein, a novel 2D/1D SnNb₂O₆/nitrogen-enriched C₃N₅ S-scheme heterojunction with strong internal electric field (IEF) and dipole field (DF) is designed through in situ growth of C₃N₅ nanorods on SnNb₂O₆ nanosheets. The IEF generated at the interface via the formation of the S-scheme heterojunction induces directional charge transfer from SnNb₂O₆ to C₃N₅. Simultaneously, the DF within C₃N₅ provides the impetus to guide photo-excited electrons to the active sites. Consequently, the synergistic effects of IEF and DF facilitate swift directional electron transfer. The optimized SnNb₂O₆/C₃N₅ heterojunction demonstrates a remarkable H₂ production rate of 1090.0 μmol∙g⁻¹∙h⁻¹ with continuous release of H₂ bubbles. This performance surpasses that of SnNb₂O₆ and C₃N₅ by 38.8 and 10.7 times, respectively. Additionally, the SnNb₂O₆/C₃N₅ heterojunction exhibits superior activity in the removal of Rhodamine B, tetracycline, and Cr(VI). Based on electron paramagnetic resonance (EPR), time-resolved photoluminescence (TPRL) and density functional theory (DFT) calculations, etc., the directional charge transfer mechanism was systematically explored. The research furnishes a plausible approach to construct effective heterojunction photocatalysts for applications in energy and environmental domains.

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