Quantum dots modified bismuth-based hierarchical dual Z-scheme heterojunction for photocatalytic performance enhancement: Mineralization, degradation pathways and mechanism

Solar-driven photocatalytic degradation is identified as a prospective technology in the realization of novel development in environmental remediation. In this work, the oriented (102) facets of BiOCl exhibited growth inhibition through microwave introducing (131) facets of Bi2MoO6. The specific Bi2MoO6/BiOCl construction pattern (BMO/BOCl) skillfully regulated the surface charge property, which was driven to couple with highly exposed active CdS quantum dots (QDs) (BMO/BOCl/CdS) via a novel room-temperature template synthesis. The conventional Type II heterojunction was transferred into dual Z-scheme heterojunction with the addition of CdS, which was successfully employed to degrade ciprofloxacin (CIP) under visible light irradiation. In the ternary BMO/BOCl/CdS system, QDs sensitized the catalyst and enhanced the response of visible light absorption. The hole of CdS was consumed with the optimal path, avoiding the photo-corrosion caused by the oxidation of S2−, which also retained the high redox capacity of the system. The regulated path consumed the hole of the CdS and maintained rapid electron-hole separation and high redox ability of the system. This was advantageous for enhancing the photocatalytic activity, especially with the optimized heterojunction, e.g. 100-BMO/BOCl/CdS exhibited distinguished photocatalytic activity of 96% CIP degradation under visible light irradiation. Furthermore, the constructed 100-BMO/BOCl/CdS heterojunction exhibited robust stability, which preserved high photocatalytic activity even after six cycles of degradation tests.