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

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 -lightdriven 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.