Insights into the critical dual-effect of acid treatment on ZnxCd1-xS for enhanced photocatalytic production of syngas under visible light

Defects induced by acid treatment over semiconductors have significant influences on photocatalytic reactions. However, acid treatment created phase transformation and generation of anion vacancies is rarely addressed. Herein, Zn0.5Cd0.5S nanocrystals are treated in acidic solutions, which generate phase transition from sphalerite to wurtzite structure and induce increase of the sulfur vacancies (Sv). It is proposed that the phase transformation and distortion promote the generation of sulfur vacancies. The dual effect of acid treatment not only provides more active sites but also enhances the charge carriers separation during the photocatalytic production of syngas from H2O and CO2. Owning to the dual effect of co-existed phases and sulfur vacancies, the Sv-rich Zn0.5Cd0.5S acquires 2.58 times CO evolution as pristine Zn0.5Cd0.5S in photocatalytic CO2 reduction under irradiation of visible light. The designed photocatalyst with phase transformation and anion vacancies provide a facile approach for fabricating efficient photocatalysts.