Sunlight-driven photocatalytic degradation of organic dyes in wastewater by chemically fabricated ZnO/Cs4SiW12O40 nanoheterojunction

Nanosized heterojunction is an attractive nanophotocatalyst for removing organic pollutants under activation by simulated sunlight. Herein, we synthesized a ZnO/Cs4SiW12O40 nanoheterojunction through a chemical approach. ZnO nanoparticles (NPs) with a diameter of approximately 200 nm were prepared by the hydrothermal method, while Cs4SiW12O40 nanospheres were synthesized by a solution route. The band gap of the constructed ZnO/Cs4SiW12O40 nanoheterojunction reached 2.65 eV, with an optical response threshold of 467 nm. Under simulated sunlight, the nanoheterojunction could degrade as much as 85.7% of Rhodamine B (RhB) in 90 min. Moreover, the nanoheterojunctions retained their excellent photocatalytic performance (76.9%) even after being recycled four times. The scavenging test of the free radical illustrated that the hole, hydroxyl radical, and superoxide anion radical are the main active radicals in the photocatalytic process. In addition, an electrochemical test demonstrated that the photogenerated carriers could be separated considerably well because the heterojunction structure has a suitable energy band alignment between ZnO and Cs4SiW12O40. The present work illustrates that ZnO/Cs4SiW12O40 nanoheterojunctions can prove highly useful for environmental remediation.