Construction of The Heterojunction with Basic Bismuth Nitrates and CuCr-Cl-LDH for Enhanced Photocatalytic Degradation of Tetracycline Under Visible-light

Layered double hydroxides (LDH) present advantages in photocatalytic degradation of organic pollutants due to excellent adsorption capacity, special layered structure, robust responsiveness to ultraviolet and visible light, etc. In order to improve the utilization efficiency of photo-generated charges, in this work, we combined basic bismuth nitrates (BBN) with CuCr-Cl-LDH to fabricate a heterojunction composite. The target heterojunction was synthesized by hydrothermal method. The resulted composites were characterized by techniques such as XRD, XPS, SEM, TEM, UV–vis DRS, BET and electrochemical performance test. The structure, morphology, optical and electrochemical performance were discussed. The results showed that the combination of BBN and CuCr-Cl-LDH formed the S-scheme heterojunction, promoting the separation of electrons and holes and remarkably improving the photocatalytic activity of CuCr-Cl-LDH. The composite that prepared by combination of 7.95 g of Bi (NO3)3·5H2O with 1 g of CuCr-Cl-LDH presented the optimal photocatalytic degradation efficiency of 96% after 2 h irradiation by visible-light at condition as photocatalyst dosage of 0.5 g·L–1 and initial tetracycline (TC) concentration of 20 mg·L–1. During the photocatalytic degradation process, the main active radicals were h+, followed by •O2–, and •OH took a relative weak role. After use of 3 cycles, the heterojunction remained the photocatalytic efficiency of 82%, showing a preliminary feasibility to application in wastewater treatment.