Sunlight-driven sustainable production of hydrogen peroxide using a CdS–graphene hybrid photocatalyst

[Display omitted] •Preparation of CdS-based photocatalysts by a hydrothermal method.•Production of hydrogen peroxide from water and oxygen.•Temperature- and pH-dependent production of hydrogen peroxide. We demonstrate the sustainable production of H2O2 without organic electron donors by a CdS-reduced graphene oxide (RGO) photocatalyst in sunlight with water and oxygen as resources. Photocatalysts were prepared with various amounts of RGO (0–30wt.% with respect to CdS) by a hydrothermal method. A photocatalyst containing 20wt.% RGO (CdS-G2) showed maximum activity, and the amount of H2O2 produced (128μM) was almost five times higher than that produced by CdS nanoparticles (27μM) after 12h sunlight irradiation. The results clearly revealed that the photocatalytic reactionmainly proceeds by two-electron reduction of oxygenrather than water oxidation on the catalyst surface. The effects of reaction temperature and pH on the production of H2O2 were also investigated. We found that the production of H2O2was enhanced at lower temperature and pH. The concentration of H2O2 reachedto 164 and 156μM with CdS-G2 at 10°C and pH 2, respectively.