S vacancy modulated Zn_xCd_1−xS/CoP quantum dots for efficient H₂ evolution from water splitting under visible light

Energy band structure and interfacial compatibility of heterojunctions are crucial for photocatalysts in promoting photogenerated charge separation and transfer. Here, a combined strategy of vacancy engineering and quantum effect via a facile phosphating process is reported, for the first time, to modulate the energy band structure and the interface of ZnxCd1-xS/CoP quantum dots (ZCSv/CoP QDs) heterojunction. The combined experimental and theoretical investigation revealed that phosphating process transformed CoOx QDs to CoP QDs, and more importantly, generated considerable amount of sulfur vacancies in ZCSv. As a result, a Type II ZCSv/CoP QDs heterojunction with compatible interfaces was constructed via in-situ generated P-Zn, P-Cd and S-Co bonds, which facilitated the separation and transfer of the photogenerated charge and thus resulted in a high ability towards hydrogen evolution under visible light. This work provides an effective and adaptable strategy to modulate band structure and interfacial compatibility of heterojunctions via vacancy engineering and quantum effect