New insights into the synergistic effect of active radicals and adsorptive ability on the photodegradation of gaseous acetaldehyde over reduced graphene Oxide/P25 composite.

Although coupling reduced graphene oxide (RGO) with TiO2 is believed to enhance the photocatalysis through the light utilization, studies on its photothermal conversion effect are rarely reported. Herein, RGOP (reduced graphene oxide/P25) was synthesized to explore roles of the enhanced light adsorption and photothermal conversion in the photocatalytic process. It was found that although RGOP had increased absorbance, it actually possessed lower available light utilization compared with P25. In the synergistic effect of available light utilization, transfer resistance and hydrophilicity, RGOP exhibited less superoxide radicals but more hydroxyl radicals. In the presence of scavenger experiments, O2- was proved to play the predominant role in the photocatalytic process, while OH was the secondary one. In comparison to P25, the change of active radicals of RGOP was adverse to its photocatalysis. However, due to the superior adsorptive property of RGOP, it exhibited higher photocatalytic activity than P25. The improved photocatalytic activity of RGOP was ascribed to its superior adsorptive ability aside from active radicals (O2-, OH).