Top or Bottom, Assembling Modules Determine the Photocatalytic Property of the Sheetlike Nanostructured Hybrid Photocatalyst Composed with Sn3O4 and rGO (GQD)

The outstanding visible-light photocatalytic properties of Sn3O4 nanosheets and excellent electron-trapping-ability-induced photoinduced-carrier-separation enhancement ability of zero-band rGO (reduced graphene oxide) nanosheets are well-known. Therefore, integration of Sn3O4 nanosheets and rGO nanosheets to prepared hybrid nanostructures has been thought of as a general strategy for synthesis of high-performance photocatalysts. However, the structural and property difference of assembling modules, such as decoration of GQDs (graphene quantum dots) on Sn3O4 nanoflakes, or distributing Sn3O4 nanoflakes on rGO nanosheets, could be the key to design high-performance Sn3O4/rGO hybrid photocatalysts. Up to now, there is no literature relating to this topic. Here, a simple microwave-assisted hydrothermal method has been reported for the fabrication of Sn3O4/GQD and Sn3O4/rGO sheetlike nano-heterostructured hybrid photocatalysts. Two photocatalysts following a different assembling modulus appeared to have different photocatalytic performances. The visible-light-active Sn3O4/GQD sheetlike nano-heterostructured hybrids show efficient and stable photocatalytic water splitting, the rate of H2 (hydrogen) evolution reaching 90 μmol/(g h), a rate 4.5 times higher than that of Sn3O4/rGO and 20 times than that of benign Sn3O4. The underlying mechanism has been investigated by photoelectrochemical measurement, ERS (electron spin-resonance spectroscopy), and PL (photoluminescence) spectra analysis. The present work demonstrates a facile method for synthesizing highly active photocatalysts for solar hydrogen generation, and gave an outline for the design of graphene-based sheetlike photocatalysts.