Microwave assisted sol–gel approach for Zr doped TiO2 as a benign photocatalyst for bismark brown red dye pollutant

Abstract

A microwave supported sol–gel approach was developed in this study to fabricate Zr-doped TiO₂ mesoporous nanostructures for efficient photocatalytic activity on bismark brown red (BBR) dye under visible light illumination. Sophisticated analytical techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM) with energy dispersive X-ray spectroscopy (EDX), X-ray fluorescence analysis (XRF), Fourier transform infrared (FT-IR), ultraviolet-visible diffuse reflectance (UV-vis-DRS) spectroscopy and Brunauer–Emmet–Teller (BET) surface area analyses were used to obtain their structural, electrical: optical and spectroscopic characteristics. The analysis results revealed that the developed nanostructures exhibited strong broad absorption in the visible region with good adsorption capacity and thus enhanced photocatalytic performance. The average crystallite size was found to be 12.5 nm (UTO), 6.4 nm (ZT₄), and 4.7 nm (ZT₄M₄) respectively. The nanocatalysts (ZT₄M₄) showed a decrease in bandgap and particle size with an increase in the surface area of the Zr-TiO₂ nanoparticles (119 m² g⁻¹). In comparison to previous studies on the photocatalytic degradation of BBR dye under visible light irradiation employing Ni–S co-doped (110 min), Cu-doped TiO2 (75 min), etc., ZT₄M₄ exhibited a remarkable degradation rate of 99% in 50 minutes. This may be due to the hydroxyl radicals being the principle reactive species responsible for the BBR dye oxidative degradation. The present study showed that ZT₄M₄ was found to be the best photocatalyst for the BBR dye degradation under the optimal conditions.