Introduction of Fe on rGO/TiO₂ improves styrene visible light-driven photocatalytic oxidation: Characterization, stability, kinetics, and mechanism

Photocatalytic process is a preferable strategy for air pollutant removal due to its high efficiency and mild operating condition. In this study, co-doping of reduced graphene oxide (rGO) and Fe were performed on TiO₂ to enhance styrene removal. Addition of 0.1 wt% rGO promoted the photocatalytic activity of TiO₂ and further improvement was achieved by introduction of Fe. The best photocatalytic activity was achieved by 0.1 wt%rGO/Fe_0.5%/TiO₂ which might be carried out by changes in reduction of band gap and electron-hole pair recombination rate. This result was also proven by the characterization analyses along with the detection of [rad]OH radicals which played an important role in the photocatalytic degradation of styrene. 1 % relative humidity accelerated photocatalytic degradation of styrene due to supply of [rad]OH radical species, however, excess amount of water vapor led to declining of photocatalytic activity due to adsorption competition on active sites. Furthermore, kinetics study using Langmuir Hinshelwood kinetics model 4 performed the best fitting with experimental data and proposed photocatalytic reaction mechanism was also built from analysis of generated intermediates.