Influence of GO oxidation degrees on the organization and physical features of TiO2–GO-based nanocomposites for water dye removal

Abstract

Graphene oxides (GO) with different oxidation degrees have been associated with TiO2 nanoparticles by a photosonication process, with ratios of 98 wt% TiO2 and 2 wt% GO. The incorporation leads to the formation of core–shell type hybrid structures with versatile structural features on the surface as a consequence of the oxidation of the adsorbed GO. Structural properties and morphology of the nanocomposites were investigated by using XRD, Raman, and SEM-TEM techniques. EPR spectroscopy confirmed the effect of photosonication through the formation of Ti3+ surface defects that are paramagnetic species. The adsorption of GO led to the formation of Ti-O-C chemical bonds, which contribute to limit the concentration of Ti3+ surface defects. The visible-light-driven photocatalytic efficiency of the nanocomposites was investigated in water remediation experiments through the removal of methylene blue (MB) dyes by combined adsorption-photocatalysis processes. The present work contributes to the understanding of the structure–properties relationships of hybrid nanocomposites and highlights the importance of the oxidation degree of GO to achieve highly efficient photocatalysts for the degradation of pollutants in water.