Reduction of graphene oxide at room temperature with vitamin C for RGO–TiO2 photoanodes in dye-sensitized solar cell

• We produce reduced graphene (RGO)–TiO2 nanocomposite at room temperature.
• The reduction is realized by vitamin C in a simple and environment-friendly way.
• Reduced graphene provides a highway for electron transportation.
• The RGO–P25 composite films are used as photoanode for DSSC.
• Conversion efficiency of 30% increase (to 7.89%) is obtained by RGO–P25 photoanode.

Graphene has been used to enhance conversion efficiency in dye-sensitized solar cell (DSSC) through increased electronic transportation. Introduction of graphene into DSSC is realized through reduction of graphene oxide (GO) to reduced graphene or RGO in TiO2 nanoparticles in solution. Chemical and hydrothermal reactions are two commonly used avenues. In the chemical route, toxic hydrazine and its derivatives are the typical reducing agent. Hydrothermal process is not toxic but requires prolonged heating. In this study, we mix flakes of GO with TiO2 nanoparticles and use vitamin C to realize the reduction at room temperature. The RGO–TiO2 composite films are then used as photoanode in DSSC. A conversion efficiency of 30% increase (to 7.89%) is obtained as compared to that of the pure TiO2 photoanode.