Herein, we present the successful synthesis of a new graphene oxide-doped-oxygen-rich TiO2 (GO-OTiO2) hybrid heterostructure through a facile wet chemical impregnation technique. The photocatalytic performances of all samples were evaluated through the photoreduction of CO2 under the irradiation of low-power energy-saving daylight bulbs. Pure oxygen-rich TiO2 (O-2-TiO2) was first prepared via a simple aqueous peroxo-titanate route. The as-prepared photocatalyst was shown to exhibit reduced band gap energy and visible-light-active characteristics. However, the photoactivity of bare O-2-TiO2 was found to gradually deteriorate over time. Hence, by exploiting its unique properties, graphene oxide (GO) was subsequently incorporated with the O-2-TiO2 photocatalyst It was observed that the photostability of the resulting GO-OTiO2 composite was significantly enhanced, where it maintained a reactivity of 95.8% even after 6 h of light irradiation. This observation firmly established the role of GO as an effective catalyst mat for O-2-TiO2 nanoparticles where it accepted photoinduced electrons and reduced the probability of charge recombination. In the CO2 photoreduction experiments, 5GO-OTiO2 with an optimum GO loading of 5 wt.%, exhibited the highest photoactivity, achieving a total CH4 yield of 1.718 mu mol/g(cat) after 6 h of reaction. The total product yield obtained over 5GO-OTiO2 was found to be 14.0 folds higher in comparison to commercial Degussa P25. In overall, we systematically demonstrated an unprecedented proof-of-concept study on enhancing the photoactivity of GO-OTiO2 via a combined strategy of fabricating visible-light-responsive O-2-TiO2 and increasing its photostability by incorporating GO sheets. (C) 2015 Elsevier B.V. All rights reserved.
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