Formulation of microwave assisted Z-scheme MoS2@TiO2: explored physicochemical properties and photodegradation of MO dye

Abstract

We propose a novel approach to achieve high pollutant degradation efficiency through the use of a visible light harvesting, microwave-assisted Z-scheme MoS2@TiO2 (MST) photocatalyst. The development of pure MST nanomaterial is confirmed through X-ray diffraction and Fourier transform infrared spectroscopy analysis. Optical absorption in the range of 200–1100 nm is examined using UV–visible spectroscopy, and the optical band gap of MST is calculated to be 2.1 eV based on Tauc’s plot. The morphological images clearly show the accumulation of particles, indicating the formation of various nanostructures such as sheets, spheres, and rods within the MST nanomaterial. To assess the practical photocatalytic activity, the degradation of methyl orange (MO), a toxic organic dye, is conducted during the daytime using the as-prepared MST. The photocatalytic performance of MST surpasses that of P25 TiO2 under visible light. This superiority can be attributed to MST's narrow bandgap and the Z-scheme, which reduce the rate of reunion of photoinduced ions. The efficacy of MST heterojunction in degrading MO dye reaches approximately 95.5% within 35 minutes, with a pseudo-first-order rate constant (k) of 0.0365 min−1. This outstanding photocatalytic performance under sunlight is attributed to MST's large specific surface area, its nanosheet, rods, and spheres-like structures, narrow bandgap, and sufficient active sites. BET and FE-SEM investigations also support these results. Moreover, the repeatability tests consisting of six consecutive cycles demonstrate that the degradation efficiency of MST is significantly higher than that of reported MoS2@TiO2 composite photocatalysts.