Titanium dioxide–gold nanocomposite materials embedded in silicate sol–gel film catalyst for simultaneous photodegradation of hexavalent chromium and methylene blue

Abstract

Aminosilicate sol–gel supported titanium dioxide–gold (EDAS/(TiO 2–Au) nps) nanocomposite materials were synthesized by simple deposition–precipitation method and characterized. The photocatalytic oxidation and reduction activity of the EDAS/(TiO 2–Au) nps film was evaluated using hexavalent chromium (Cr(VI)) and methylene blue (MB) dye under irradiation. The photocatalytic reduction of Cr(VI) to Cr(III) was studied in the presence of hole scavengers such as oxalic acid (OA) and methylene blue (MB). The photocatalytic degradation of MB was investigated in the presence and absence of Cr(VI). Presence of Au nps on the (TiO 2) nps surface and its dispersion in the silicate sol-gel film (EDAS/(TiO 2–Au) nps) improved the photocatalytic reduction of Cr(VI) and oxidation of MB due to the effective interfacial electron transfer from the conduction band of the TiO 2 to Au nps by minimizing the charge recombination process when compared to the TiO 2 and (TiO 2–Au) nps in the absence of EDAS. The EDAS/(TiO 2–Au) nps nanocomposite materials provided beneficial role in the environmental remediation and purification process through synergistic photocatalytic activity by an advanced oxidation–reduction processes.