Silicate sol–gel matrix stabilized ZnO–Ag nanocomposites materials and their environmental remediation applications

Abstract

A facile preparation method was employed to decorate the zinc oxide nanoparticles by aminosilicate sol-gel supported silver nanoparticles (TPDT/(ZnO-Ag) NCMs). The nanocomposite photocatalyst materials were characterized by UV–vis absorption spectra, DRS, XRD, SEM and EDX techniques. The absorption spectral studies showed that the Ag nanoparticles (Ag NPs) were deposited on the ZnO nanoparticles (ZnO NPs) (represented as TPDT/(ZnO-Ag) NCMs) and the NCMs are highly stable. The photocatalytic oxidation and reduction reactions at the TPDT/(ZnO-Ag) NCMs photocatalysts were evaluated by using the toxic methylene blue (MB) dye and hexavalent chromium (Cr(VI)), respectively under visible light irradiation. The photocatalytic activity of the NCMs showed that the MB dye was completely decolorized at TPDT/(ZnO-Ag) 0.1 NCMs photocatalyst when compared to the controlled photocatalyst materials. The photocatalytic reduction of highly toxic Cr(VI) to less toxic Cr(III) was studied at the photocatalyst TPDT/(ZnO-Ag) 0.5 NCMs in the presence of hole scavengers such as oxalic acid. The Ag NPs deposited on the ZnO NPs and dispersed in silicate sol-gel matrix (TPDT/(ZnO-Ag) NCMs) improved the photocatalytic activity of the ZnO NPs photocatalyst with effective interfacial electron transfer processes at the ZnO by minimizing the charge recombination process when compared to the bare ZnO NPs. The TPDT/(ZnO-Ag) NCMs showed promising environmental remediation and water purification processes through the synergistic photocatalytic activity by advanced oxidation-reduction processes.