Synthesis, characterization and enhanced photocatalytic CO2 reduction activity of graphene supported TiO2 nanocrystals with coexposed {001} and {101} facets

Abstract

It is known that the combination of TiO₂ and graphene and the control of TiO₂ crystal facets are both effective routes to improve the photocatalytic performance of TiO₂. Here, we report the synthesis and the photocatalytic CO₂ reduction performance of graphene supported TiO₂ nanocrystals with coexposed {001} and {101} facets (G/TiO₂-001/101). The combination of TiO₂ and graphene enhanced the crystallinity of TiO₂ single nanocrystals and obviously improved their dispersion on graphene. The “surface heterojunction” formed by the coexposed {001} and {101} facets can promote the spatial separation of photogenerated electrons and holes toward different facets and the supports of graphene can further enhance the separation through accelerated electron migration from TiO₂ to graphene. The G/TiO₂-001/101 exhibited high photocatalytic CO₂-reduction activity with a maximum CO yield reaching 70.8 μmol g⁻¹ h⁻¹. The enhanced photocatalytic activity of the composites can be attributed to their high surface area, good dispersion of TiO₂ nanoparticles, and effective separation of excited charges due to the synergy of graphene supports and the co-exposure of {001} and {101} facets.