Effectively compound the heterojunction formed by flower-like Bi2S3 and g-C3N4 to enhance photocatalytic activity

In this study, the flower-shaped Bi 2 S 3 /g-C 3 N 4 -2.6 heterojunction obtained by solvothermal method and its photocatalytic degradation efficiency of rhodamine B (RhB) and tetracycline (TC) in aqueous solution within 40 min is as high as 98.8% and 94.6%. For RhB degradation, the photocatalytic reaction rate constant (k) of Bi 2 S 3 /g-C 3 N 4 -2.6 is approximately 1.8 and 45.5 times that of Bi 2 S 3 and g-C 3 N 4 . For TC, k is 3.1 and 2.4 times that of Bi 2 S 3 and g-C 3 N 4 , respectively. The key to determining the high catalytic activity of Bi 2 S 3 /g-C 3 N 4 lies in the formation of a good heterojunction between Bi 2 S 3 and g-C 3 N 4 , which accelerates the electron transfer rate between the heterojunction interface and effectively avoids electron–hole recombination. The effects of catalyst dosage, different pH values, inorganic anions, and capture agents on the photodegradation performance of RhB were investigated. The results show that the catalyst dosage is 1.33 g/L, and the solution pH is in the range of 5–9, which has the best removal effect on pollutants, and the isolation of holes ( h + ) with strong oxidizing ability promotes the collapse of pollutant molecules. Combined with electrochemical tests, a possible degradation mechanism was advised.