Graphene Quantum Dots Incorporated SnO2 Composites with Improved Photoelectric Properties

SnO2 based composites were prepared in this study via solvothermal method, using SnCl4 center dot 5H(2)O as Sn precursors and micrometer or nanometer-sized graphene as supports. Micrometer-sized graphene sheets were cut into nanometer-sized graphene quantum dots had interlamellar spacing of 0.34 nm and 0.24 nm attributed to (002) and (1120) crystal facets of graphene quantum dots. GQDs attached SnO2 composites presented with interlamellar spacing of 0.35 nm and 0.26 nm, designated to the (110) and (101) crystal facets of SnO2. The incorporation of SnO2 with GQDs led to decreased zeta potential from 12.99 to -7.2 mV, due to electrostatic interaction between positively charged SnO2 and highly negative GQDs. The performances of SnO2 based composites were investigated by photocurrent-time and electrochemical impedance measurements. The SnO2/graphene quantum dots composites presented higher photocurrent density and lower charge-transfer resistance in comparison with SnO2/graphene composites. The photocurrent response of the former was about four times higher than that of the latter, which indicated that the incorporation of graphene quantum dots decreased conductive distance, inhibiting charge recombination and improving electron transfer.