Construction and enhanced efficiency of Z-scheme-based ZnCdS/Bi2WO6 composites for visible-light-driven photocatalytic dye degradation

Novel ZnCdS/Bi2WO6 composites have been prepared through a three-step method. The products have proved to be highly effective in the photodegradation of malachite green (MG) under visible light, while also showing outstanding stability. The excellent photocatalytic performance of the composites can be primarily attributed to effective separation and migration of electrons and holes across their tight contact interfaces, which conform to a Z-scheme heterostructure. Free radical capture experiments have verified that hydroxyl radicals (center dot OH) and superoxide ion radicals (center dot O-2(-)) play decisive roles in the reaction process. A putative photocatalytic mechanism over ZnCdS/Bi2WO6 is proposed, providing a rationale for its enhanced photocatalytic activity. This work provides a perspective for the design of ZnCdS/Bi2WO6 photocatalysts with a Z-scheme heterostructure that can not only utilize solar energy more effectively, but may also provide a new concept for environmental remediation.