Efficient visible-light-driven photocatalytic hydrogen production using CdS@TaON coreshell composites coupled with graphene oxide nanosheetsElectronic supplementary information (ESI) available: Experiments for synthesis of CdS@TaON composites prepared by a hydrothermal process and a solvothermal route; Fig. S1: UV-vis spectra for CdS@TaON composites with different contents of CdS nanocrystals; Fig. S2: XRD patterns of GOCdS@TaON composites with different contents of GO; Fig. S3: TEM image of CdS

Large-scale hydrogen production through water splitting using photocatalysts with solar energy can potentially produce clean fuel from renewable resources. In this work, photocatalytic evolution of H 2 with a high efficiency was achieved using graphene oxide (GO) nanosheets decorated with CdS sensitized TaON coreshell composites (GOCdS@TaON). The CdS@TaON coreshell nanocomposites were prepared by an ion-exchange route with assistance from a hydrothermal process on GO as the support. The TaON coreshell composites containing 1 wt% CdS nanocrystals showed a high rate of H 2 -production at 306 mol h 1 with an apparent quantum efficiency (QE) of 15% under 420 nm monochromatic light. The rate of hydrogen formation was 68 times faster in comparison with the rate observed on pure TaON. The rate was further increased to 633 mol h 1 with a high quantum efficiency of 31% when the GOCdS@TaON hybrid composite was coupled with 1 wt% of graphene oxide and 0.4 wt% of Pt (about 141 times higher than that of the pristine TaON). This high photocatalytic H 2 -production activity is ascribed firstly to the presence of CdS nanocrystals that alter the energy levels of the conduction and valence bands in the coupled semiconductor system; secondly to the involvement of graphene oxide that serves as an electron collector and transporter to efficiently lengthen the lifetime of the photogenerated charge carriers from CdS@TaON composites. This investigation can open up new possibilities for the development of highly efficient TaON-based photocatalysts that utilize visible light as an energy source. The CdS@TaON coreshell composites coupled with graphene nanosheets show an excellent photocatalytic activity for large-scale hydrogen production under visible-light irradiation.