Synthesis and application of novel mesoporous-assembled SrTixZr1−xO3-based nanocrystal photocatalysts for azo dye degradation

In this work, novel mesoporous-assembled SrTixZr1−xO3 nanocrystal photocatalysts were successfully synthesized by a sol–gel process with the aid of a structure-directing surfactant under mild conditions. The photocatalytic activity of the synthesized photocatalysts for degradation of Acid Black (AB) diazo dye used as a model contaminant in textile wastewater was investigated by varying Ti-to-Zr molar fraction, calcination conditions, and Pt loading. The synthesized photocatalysts were systematically characterized by TG–DTA, N2 adsorption–desorption analysis, XRD, UV–visible spectroscopy, SEM–EDX, TEM–EDX, TPR, and H2 chemisorption. The photocatalytic activity results showed that without Pt loading, the mesoporous-assembled SrTixZr1−xO3 photocatalyst with a Ti-to-Zr molar fraction of 0.9:0.1 (i.e. SrTi0.9Zr0.1O3) calcined at 700 °C for 4 h provided a maximum degradation rate constant as compared to the other SrTixZr1−xO3 photocatalysts. The optimum Pt loading of 1 wt.% by a single-step sol–gel method on the mesoporous-assembled SrTi0.9Zr0.1O3 photocatalyst was found to greatly increase the degradation rate constant of the AB dye. Furthermore, the calcination temperature was found to significantly affect the degradation rate constant of the Pt-loaded mesoporous-assembled SrTi0.9Zr0.1O3 photocatalyst.