Efficient solar light-driven hydrogen generation using an SnO nanoflake/graphene nanoheterostructure.

Herein, we report SnO and SnO nanoflake/graphene for photocatalytic hydrogen generation from HO and HS under natural "sunlight" irradiation. The SnO/graphene composites were prepared by a simple hydrothermal method at relatively low temperatures (150 °C). The incorporation of graphene in SnO exhibits remarkable improvement in solar light absorption, with improved photoinduced charge separation due to formation of the heterostructure. The highest photocatalytic hydrogen production rate for the SnO/graphene nanoheterostructure was observed as 4687 μmol h g from HO and 7887 μmol h g from HS under natural sunlight. The observed hydrogen evolution is much higher than that for pure SnO (5.7 times that from HO, and 2.2 times from HS). The improved photocatalytic activity is due to the presence of graphene, which acts as an electron collector and transporter in the heterostructure. More significantly, the SnO nanoflakes are uniformly and parallel grown on the graphene surface, which accelerates the fast transport of electrons due to the short diffusion distance. Such a unique morphology for the SnO along with the graphene provides more adsorption sites, which are effective for photocatalytic reactions under solar light. This work suggests an effective strategy towards designing the surfaces of various oxides with graphene nanoheterostructures for high performance of energy-conversion devices.