Facile synthesize of CdS QDs decorated Bi2MoO6/Bi2Mo3O12 heterojunction photocatalysts and enhanced performance of visible light removal of organic pollutants.

In this work, the CdS quantum dots (QDs) decorated Bi2MoO6/Bi2Mo3O12 (BMO) heterojunction photocatalyst (C/BMO) has been successfully synthesized using a facile two-step hydrothermal method. The as-prepared photocatalysts were characterized by XRD, FTIR, XPS, FESEM, TEM, UV-vis DRS, PL and photoelectrochemical measurements to investigate the effects of CdS(QDs) and BMO heterojunction on the structure, morphology, optical and charge carrier transmission characteristics of the photocatalysts. Narrow band gap and superior catalytic activities were found in C/BMO as compared with pure BMO. Moreover, the C/BMO photocatalyst containing twice CdS content (2-C/BMO) exhibits even higher photocatalytic activity and stability. After exposure to visible light for 30 min, the degradation rate of Rhodamine B (RhB), Methylene blue (MB) and Ofloxacin (OFX) by 2-C/BMO reached 95%, 92% and 76%, respectively. Radicals scavenging experiments and electron spin-resonance spectroscopy (ESR) investigations indicated that the superoxide radical anions (∙O2- ), hole (h+) and hydroxyl radicals (•OH) are the dominating active species in the photodegradation processes. ∙O2- and h+ are the key factors in the degradation of RhB and OFX solutions, and •OH is the major determinant in removal of MB. The process and photocatalytic mechanism on 2-C/BMO was discussed. Well absorption of visible light, effective separation of photoelectron-hole pairs and the transportation of photogenerated carriers at the interfaces of ternary semiconductor heterojunction are suggested as the key factors to enhance the photocatalytic performance of the photocatalysts.