In-situ construction of 2D/1D Bi₂O₂CO₃ nanoflake/S-doped g-C₃N₄ hollow tube hierarchical heterostructure with enhanced visible-light photocatalytic activity

The construction of heterojunction photocatalysts was considered to be an effective strategy to tackle refractory pollutants. However, most of the reported composites lacked precise control of their morphology, resulting in unsatisfactory catalytic activity. In this work, we successfully fabricated sulfur doped g-C₃N₄ hollow tubes (SCN) via molecular self-assembly, and then grew the Bi₂O₂CO₃ nanoflakes (BOC) in situ parallel on the surface of SCN to construct 2D/1D interfacial phase. Within 30 min visible light irradiation, the robust BOC/SCN-3 heterostructure showed considerable improvement for tetracycline degradation (82.6%) compared with individual components. This enhanced photocatalytic performance derived from the synergistic effect of S doping and heterojunction interface contact. The tubular structure formed by S doping not only narrowed the bandgap and thus boosting the visible light harvesting of CN, but also promoted electrons to travel along the 1D longitudinal and radial directions. In addition, the built-in electric field between BOC and SCN effectively achieved the spatial separation of electron-hole pairs. Mechanism analysis revealed that the h⁺ and •O₂⁻ radicals played the dominating contribution in the photocatalytic process, and a possible Z-scheme mechanism was proposed. It was expected that such design route could provide a new perspective on hierarchical heterostructure for pollutant removal.