Supercritical fluid mediated synthesis of highly exfoliated graphene/ZnO composite for photocatalytic hydrogen production

•One-pot green synthesis using supercritical fluid.•Size uniformity and appropriate dispersion.•No residual impurities.•RGO/ZnO composite as an efficient photocatalyst for hydrogen production.•Improved interfacial charge transfer between ZnO and RGO.

Reduced graphene oxide (RGO)/zinc oxide (ZnO) composite was synthesized via a simple and environmentally-friendly route using supercritical carbon dioxide. The structure and morphology of the resulting composite was characterized by transmission electron microscopy, X-ray diffraction and Raman spectroscopy. The nanocomposite exhibited enhanced photocatalytic activity for hydrogen (H2) production from water photo-splitting because the ZnO nanoparticles on the RGO sheets can capture light energy and facilitate excited electron transfer for photocatalytic H2 production via RGO, which acts as an efficient electron mediator.