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Nano Research

Article Title

Self-assembly of nitrogen-doped TiO2 with exposed {001} facets on a graphene scaffold as photo-active hybrid nanostructures for reduction of carbon dioxide to methane

Keywords

photocatalysis, nitrogen-doped TiO2, {001} facet, acid treated solvent exfoliated graphene, carbon dioxide reduction, visible light

Abstract

Tailored synthesis of well-defined anatase TiO2-based crystals with exposed {001} facets has stimulated incessant research interest worldwide due to their scientific and technological importance. Herein, anatase nitrogen-doped TiO2 (N–TiO2) nanoparticles with exposed {001} facets deposited on the graphene (GR) sheets (N–TiO2-001/GR) were synthesized for the first time via a one-step solvothermal synthetic route using NH4F as the morphology-controlling agent. The experimental results exemplified that GR was uniformly covered with anatase N–TiO2 nanoparticles (10–17 nm), exposing the {001} facets. The percentage of exposed {001} facets in the N–TiO2-001/GR nanocomposites was calculated to be ca. 35%. Also, a red shift in the absorption edge and a strong absorption in the visible light range were observed due to the formation of Ti–O–C bonds, resulting in the successful narrowing of the band gap from 3.23 to 2.9 eV. The photocatalytic activities of the as-prepared photocatalysts were evaluated for CO2 reduction to produce CH4 in the presence of water vapor under ambient temperature and atmospheric pressure using a low-power 15 W energy-saving daylight lamp as the visible light source—in contrast to the most commonly employed high-power xenon lamps—which rendered the process economically and practically feasible. Among all the studied photocatalysts, the N–TiO2-001/GR nanocomposites exhibited the greatest CH4 yield of 3.70 μmol·gcatalyst–1, approxi- mately 11-fold higher activity than the TiO2-001. The enhancement of photocatalytic performance was ascribed to the effective charge anti-recombination of graphene, high absorption of visible light region and high catalytic activity of {001} facets relative to the {101} facets.

Graphical Abstract

Publisher

Tsinghua University Press

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