Enhancing the photocatalytic activity of TiO2 and TiO2-SiO2 by coupling with graphene-gold nanocomposites

In the present paper, a novel composite Graphene-Gold (Gr-Au)/TiO2-SiO2 photocatalyst was synthesized and tested for the removal of methylene blue and rhodamine B in water solutions. First, Gr-Au nanoparticle composite was synthesized by simultaneous reduction and deposition of Au nanoparticles on Gr surface. The photodegradation of methylene blue and rhodamine B in aqueous solutions was studied using various photocatalysts, including neat TiO2-SiO2, Gr/TiO2-SiO2 and Gr-Au/TiO2-SiO2 composites. The Gr weight ratio in this research is 2% in the Gr/TiO2-SiO2 composites. Detailed characterization (field emission scanning electron microscope, Raman, Fourier transform infrared spectra and UV-vis absorbance spectroscopy) of such material was conducted. As a result, the uniform deposition of nanometer-sized Au NPs on the graphene sheets was observed. The Gr-Au/TiO2-SiO2 exhibited excellent photocatalytic efficiency because of the reduction of electron-hole recombination. The Gr2%-Au0.1%/TiO2-SiO2 composite had the highest photoactivity.

Automated summary

A novel composite Graphene-Gold/TiO2-SiO2 photocatalyst was synthesized and tested for the degradation of methylene blue and rhodamine B, showing excellent efficiency due to the reduction of electron-hole recombination. The Gr2%-Au0.1%/TiO2-SiO2 composite exhibited the highest photoactivity among all tested photocatalysts.