Preparation of dual Z-scheme PDIP/WO3@CN-Br heterojunction photocatalyst and its excellent degradation efficiency of tetracycline under visible light

Abstract

The novel all-solid PDIP/WO3@Br-doped g-C3N4 (PDIP/WO3@CN-Br) composite with a dual Z-scheme heterojunction structure was designed to remove tetracycline contaminants in water resources. The obvious improvement on the degradation efficiency for tetracycline not only originates from the more active sites provided by this system, but also results from the extended carrier life of the special heterojunction structure. Moreover, the introduction of the cocatalyst Br changes the microstructure of bulk g-C3N4 to accelerate the separation of electrons and holes, thus improving the photocatalytic performance. Upon these advantageous merits, the apparent rate constant of tetracycline degradation by the PDIP/WO3@CN-Br photocatalyst was 3.83 times higher than that of pure PDIP. Additionally, two typical degradation pathways for tetracycline were hypothesized by LC-MS and 3DEEMs tests, which systematacially demonstrated this pollutant has transformed into small molecule substances. Satisfactorily, in the simulation experiments of different water environments, this PDIP/WO3@CN-Br system showed excellent stability and practical application value. Our study provides a promising approach to design a novel dual Z-scheme heterojunction photocatalysts with full utilization of solar energy and enhance charge separation.