Promoting the oxidative removal rate of 2,4-dichlorophenoxyacetic acid on gold-doped WO3/TiO2/reduced graphene oxide photocatalysts under UV light irradiation

2,4-Dichlorophenoxyacetic acid photooxidation catalysed by nanosized TiO2, WO3/TiO2, Au/TiO2, Au/WO3/TiO2, and matching composite materials with reduced graphene oxide has been studied upon irradiation with UV light. The photocatalysts were characterised by the BET, XRD, XPS, SEM, and TEM methods as well as Raman spectroscopy and adsorption of the pollutant. Nanosized TiO2, WO3/TiO2, Au/TiO2 and Au/WO3/TiO2 particles were randomly distributed on the surface of the reduced graphene oxide nanosheets. Calculated rate constant values for 2,4-dichlorophenoxyacetic acid photooxidation upon irradiation with UV light decrease in the following order: Au/WO3/TiO2/RGO > Au/TiO2/RGO > Au/WO3/TiO2 > WO3/TiO2/RGO > Au/TiO2 > TiO2/RGO > WO3/TiO2 > TiO2. The rate constant of 2,4-dichlorophenoxyacetic acid degradation catalysed by an Au/WO3/TiO2/reduced graphene oxide composite was approximately 5.8 times higher than that registered with titania. Displayed enhanced activity of the Au/WO3/TiO2/reduced graphene oxide photocatalyst is believed to originate from a higher local concentration of the pollutant around the investigated photocatalyst and due to simultaneous charge carrier separation over both the gold nanoparticles and reduced graphene oxide sheets. (C) 2017 Elsevier B.V. All rights reserved.