Enhanced visible photocatalytic activity of nanocrystalline α-Fe2O3 by coupling phosphate-functionalized graphene

Abstract

In this work, it is clearly demonstrated that the visible photocatalytic activity for degrading colorless gas-phase acetaldehyde and liquid-phase phenol of nanocrystalline α-Fe2O3, which is synthesized by a phase-separated hydrolysis–solvothermal method, is greatly enhanced by coupling with an appropriate amount of unfunctionalized and phosphate-functionalized graphene, especially the latter. It is suggested that the enhanced activity can be attributed to the obviously increased amount of adsorbed O2 so as to promote photogenerated charge separation, as verified mainly by means of atmosphere-controlled surface photovoltage spectra, transient state surface photovoltage responses, O2 electrochemical reduction measurements, and O2 temperature-programmed desorption curves. The coupled graphene is favorable for photogenerated electrons to transfer and then separate in space. This work provides a feasible route to improve photocatalytic activity for degrading pollutants using composites of nanostructured carbon and oxides.