Construction of CoS/Bi2O2CO3 micro-flowers: Efficient degradation of tetracycline hydrochloride over a wide concentration range

(a)Proposed Z-scheme mechanism of the charge transfer and separation in the CoS/Bi 2 O 2 CO 3 composite. • The matching band gap of heterostructure greatly promotes the transfer of the carrier, which makes full use of the reducibility of the conduction band and the oxidation of the valence band. • The CoS/Bi 2 O 2 CO 3 composite exhibits a higher photocatalytic activity (96.96% for 40 mg/L TCH within 60 min) and stability. • The CoS/Bi 2 O 2 CO 3 has a huge practical application potential in the actual water environment management. (the degradation rate of 100 mg/L TCH reached more than 80% after 6 hours irradiation). • The CoS/Bi 2 O 2 CO 3 has excellent photocatalytic ability in weak acid and weak base solution. • The Z-scheme photocatalytic mechanism is demonstrated by UV-vis DRS spectroscopy and radical capture experiments. Herein, the CoS/Bi 2 O 2 CO 3 heterojunction photocatalyst was successfully fabricated using a facile solvothermal method. The as-prepared CoS/Bi 2 O 2 CO 3 heterostructure showed faster and higher photocatalytic performance in the photocatalytic oxidation of the hazardous antibiotic contaminant tetracycline hydrochloride (TCH) when compared with single Bi 2 O 2 CO 3 . The optimized 0.5% CoS/Bi 2 O 2 CO 3 sample had a photodegradation rate of 96.96% for 40 mg/L of TCH within 60 min, and the photodegradation rate of TCH within 30 min was 83.93%. Significantly, the composite exhibits efficient degradation rates for TCH solutions even at concentrations up to 100 mg/L. Thus, the main advantages of CoS/Bi 2 O 2 CO 3 composites are quick removal time and application to a broad range of contaminant concentrations. Additionally, the impact of pH level on the efficiency of the photocatalytic process was investigated. Particularly, photoelectrochemical characterizations and trapping tests revealed in-depth information about the TCH degradation mechanism. The heterojunction structure can effectively enhance the separation, transfer and synergistic effect of the support to further strengthen the photocatalytic performance. This work demonstrates a new way to prepare green and low-cost heterojunction structured photocatalysts, which can be effectively used to degrade high-concentration TCH wastewater.