Enhanced photocatalytic activities of low-bandgap TiO 2 -reduced graphene oxide nanocomposites

Abstract

In this study, a hydrothermal method was successfully used to prepare a reduced graphene oxide (RG)–titanium dioxide (TiO₂) hybrid in 10–20 nm, starting from commercial TiO₂ P25 nanoparticles and liquid-exfoliated graphene oxide (GO). Compared to TiO₂, an obvious red shift of light absorption (from 3.1 to 2.6 eV) of the as-prepared RG–TiO₂ was observed by UV–Vis analysis, and an enhanced photocatalytic degradation of the Rhodamine B (Rh. B) was also observed under Xe lamp exposure test by using the as-prepared RG–TiO₂. Multiple characterizations of this RG–TiO₂ nanocomposite confirmed that its photocatalytic enhancement could be ascribed to two approaches. Firstly, RG extended the mean free path and photogenerated electrons' lifetime of TiO₂, which minimized electron–hole pairs' recombination. Secondly, RG expanded the light absorption spectrum of TiO₂ from UV range to UV and visible light range. The explication of these improvements was concluded as the energy gap changing and a likelihood of up-conversion photoluminescence mechanism (UCPL). Due to the low-cost, nonpoisonous and excellent photocatalytic properties of RG–TiO₂, this material can be applied well in sewage treatment and other related fields.

Graphical abstract

ᅟ

http://ift.tt/2qR4o5G