Noble Metal-Free Reduced Graphene Oxide-ZnxCd1-xS Nanocomposite with Enhanced Solar Photocatalytic H2-Production Performance

Design and preparation of efficient artificial photosynthetic systems for harvesting solar energy by production of hydrogen from water splitting is of great importance from both theoretical and practical viewpoints. ZnS-based solid solutions have been fully proved to be an efficient visible-light driven photocatalysts, however, the H-2-production rate observed for these solid solutions is far from exciting and sometimes an expensive Pt cocatalyst is still needed in order to achieve higher quantum efficiency. Here, for the first time we report the high solar photocatalytic H-2-production activity over the noble metal-free reduced graphene oxide (RGO)-ZnxCd1-xS nanocomposite prepared by a facile coprecipitation-hydrothermal reduction strategy. The optimized RGO-Zn0.8Cd0.2S photocatalyst has a high H2-production rate of 1824 mu mol h(-1) g(-1) at the RGO content of 0.25 wt % and the apparent quantum efficiency of 23.4% at 420 nm (the energy conversion efficiency is ca. 0.36% at simulated one-sun (AM 1.5G) illumination). The results exhibit significantly improved photocatalytic hydrogen production by 450% compared with that of the pristine Zn0.8Cd0.2S, and are better than that of the optimized Pt-Zn0.8Cd0.2S under the same reaction conditions, showing that the RGO-Zn0.8Cd0.2S nanocomposite represents one of the most highly active metal sulfide photocatalyts in the absence of noble metal cocatalysts. This work creates a green and simple way for using RGO as a support to enhance the photocatalytic H-2-production activity of ZnxCd1-xS, and also demonstrates that RGO is a promising substitute for noble metals in photocatalytic H-2-production.