Efficient solar light-driven hydrogen generation using an Sn 3 O 4 nanoflake/graphene nanoheterostructure.

Herein, we report Sn 3 O 4 and Sn 3 O 4 nanoflake/graphene for photocatalytic hydrogen generation from H 2 O and H 2 S under natural "sunlight" irradiation. The Sn 3 O 4 /graphene composites were prepared by a simple hydrothermal method at relatively low temperatures (150 °C). The incorporation of graphene in Sn 3 O 4 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 Sn 3 O 4 /graphene nanoheterostructure was observed as 4687 μmol h -1 g -1 from H 2 O and 7887 μmol h -1 g -1 from H 2 S under natural sunlight. The observed hydrogen evolution is much higher than that for pure Sn 3 O 4 (5.7 times that from H 2 O, and 2.2 times from H 2 S). 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 Sn 3 O 4 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 Sn 3 O 4 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.