One-step hydrothermal synthesis of (CuIn)0.2Zn1.6S2 hollow sub-microspheres for efficient visible-light-driven photocatalytic hydrogen generation

(CuIn)0.2Zn1.6S2 (CIZS) hollow sub-microspheres were prepared by a simple one-step hydrothermal method using thioacetamide (TAA) as a sulfur source. It was demonstrated that the amount of TAA played a key role on the morphology of CIZS samples. Low amount of TAA led to the formation of solid sub-microspheres. Nevertheless, high amount of TAA gave rise to the growth of hollow sub-microspheres, which could be elucidated by a bubble template mechanism. The morphology transition, as well as the reduced crystallite size, led to the increased specific surface area with the increased amount of TAA. Meanwhile, the defect states in CIZS samples were gradually decreased, when the amount of TAA was increased. The improved specific surface area and decreased defects of CIZS products contributed to higher efficiencies of charge separation and surface chemical reaction. The photocatalytic performance of CIZS photocatalysts was closely influenced by the amount of TAA. CIZS samples prepared with 5 g of TAA showed the highest hydrogen production rate, with the apparent quantum yield of 11.5% at 420 nm. It was summarized that the superior photocatalytic activity should be attributed to the larger specific surface area, decreased defects and relatively clean surface. This work not only provided a simple route to prepare hollow-structured photocatalysts, but also demonstrated the importance of sulfur source on photocatalytic properties of metal sulfide photocatalysts.