Visible-light-active oxygen-rich TiO2 decorated 2D graphene oxide with enhanced photocatalytic activity toward carbon dioxide reduction

•Unprecedented graphene oxide-modified oxygen-rich TiO2 photocatalysts were prepared.•A proof-of-concept study on enhancing the photoactivity of the composite was shown.•Modifying the titanium precursor with H2O2 rendered TiO2 visible-light-responsive.•The incorporation of graphene oxide with modified TiO2 enhanced its photostability.•The optimum GO loading of 5 wt.% showed superior activity toward CO2 reduction.

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 (O2–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 O2–TiO2 was found to gradually deteriorate over time. Hence, by exploiting its unique properties, graphene oxide (GO) was subsequently incorporated with the O2–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 O2–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 μmol/gcat 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 O2–TiO2 and increasing its photostability by incorporating GO sheets.

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