Well-designed MOF-derived hollow octahedral structure TiO2 coupled with ultra-thin porous g-C3N4 to enhance the degradation of real liquor brewing wastewater

The poor visible light utilization and the quick recombination of photogenerated charge of photocatalysts are major issues dominating the application of photocatalysts in the treatment of industrial wastewater. Herein, a novel TiO2/g-C3N4 S-scheme heterojunction photocatalyst was constructed by homogeneously embedding hollow octahedral TiO2 nanoparticles (HOT) in ultra-thin porous g-C3N4 nanosheets (UPCN). SEM and TEM demonstrate that the HOT possesses hollow octahedron structure. The results of XRD, XPS and FT-IR imply that the HOT/UPCNx composites have been prepared successfully. The HOT/UPCN0.4 (mass ratio of TiO2 to g-C3N4 = 1:2) exhibits the highest chemical oxygen demand (COD) removal rate for real liquor brewing wastewater (LBW) 50.4% which is 2.2 times that of Degussa P25. After 5 cycles of performance test (25 h), the COD removal rate of HOT/UPCN0.4 was reduced by 7.1%. The excellent photocatalytic performance in the degradation of real LBW can be ascribed to the construction of S-scheme heterojunction which extending the light absorption range and providing effective channels for the separation and transfer of charge as well as hollow octahedron and porous structure which enhancing the light utilization. Moreover, the tight interface junction and large contact interface between HOT and UPCN provide more “highways” for the transfer of photogenerated charge.