Photocatalytic degradation of rhodamine B by Bi2O3@LDHs S–scheme heterojunction: Performance, kinetics and mechanism

Abstract

In this paper, based on Bi2O3 and CoAl–layered double hydroxides (LDHs), a core–shell structure S–scheme heterojunction catalyst (Bi2O3@LDHs) was synthesized and used for photodegradation of Rhodamine B (RhB), a typical dye. The effects of the amount of catalyst (A), light intensity (B), pH value (C) and reaction temperature (T) on the degradation performance were discussed. The apparent kinetic equation of RhB photodegradation catalyzed by LDHs and Bi2O3@LDHs are: ln(C/C0)=-5.661×105e-30.01×103RT×[A]00.9348×[B]o1.0348×[C]00.9965×t and ln(C/C0)=-8.398×103e-16.39×103RT×[A]01.2547×[B]o1.5279×[C]01.0197×t. Under the best reaction conditions of the amount of catalyst is 40 mg, the light intensity is 400 W, the reaction pH value is 9, and the reaction temperature is 303 K, the highest removal is 90.36%, and the activity is 37.65 mg g−1h−1. In addition, by means of radical characterization and DFT calculation, the formation mechanism of built–in electric field and the promotion of S–scheme electron transport path in heterojunction were systematically analyzed, and the degradation intermediates and degradation paths were also discussed.