Heterojunction Engineering for Boosted Interfacial Charge Separation: Intimate Face-to-Face 2D/2D SnWO4/BiOBr Z-Scheme Heterojunction for Photocatalytic Remediation

Constructing 2D/2D heterojunction is an effective strategy to suppress the recombination of photogenerated carriers and boost the photocatalytic performance of semiconductor photocatalysts. In this study, a 2D/2D direct Z-scheme SnWO 4 /BiOBr (SWO/BOB) heterojunction photocatalyst was successfully fabricated through a facile hydrothermal route. Intimate face-to-face interfacial contact between SnWO 4 nanosheets and BiOBr nanoplates was verified by multiple characterizations.The as-prepared SWO/BOB composite heterojunction photocatalysts exhibited enhanced photocatalytic activity over bare SnWO 4 and BiOBr. The optimized 50SWO/BOB sample presented the highest degradation performance. Its RhB degradation efficiency within 25 min was 2.41 and 2.95 times that of pure SnWO4 and BiOBr, respectively, while its CIP degradation efficiency in 60 min was 3.44 times and 1.27 times higher than SnWO 4 and BiOBr. The improved photocatalytic performance is mainly attributed to the unique structural advantages of the 2D/2D heterostructure, which broadens the light response range and accelerates interfacial charge transfer. Radical trapping tests confirmed that h⁺ was the primary reactive species, and ·O 2 ⁻ acted as a secondary active species in the photocatalytic pollutant degradation process of the 2D/2D heterostructure. A direct Z-scheme charge transfer mechanism was proposed based on band structure analysis and existing active species. This work provides a facile strategy for the design of high-efficiency bismuth-based 2D/2D photocatalysts and theoretical support for the remediation of refractory organic wastewater.