Facile synthesis of TiO2@MoS2 hollow microtubes for removal of organic pollutants in water treatment

Preparation and properties of floral CaO/ZnO composite from Achatina fulica snail shell

In this study, CaO prepared by calcination treatment from abandoned Achatina fulica shell was used as a raw material, and the floral CaO/ZnO photocatalytic composite material was prepared through co-precipitation method. SEM study showed ZnO with spindle-like petals in the range of 500-1000 nm grown on the surface of CaO carrier. The mapping image shows that the base component of the floral structure is mainly CaO, which is because CaO is not only in the reaction as a carrier, but also creates an alkaline environment in the methanol system, which is advantageous for co-precipitation. UV-vis spectroscopy shows that the visible light absorption of composites has red shifts; besides, PL, EIS, and photocurrent test showed that the composites have stronger electronic hole separation capabilities. The visible light degradation test of rhodamine B showed that CaO/ZnO photocatalytic composite could degrade 90% of the pollutants in 25 min, superior to CaO and ZnO, exhibiting recyclability properties, which is a potential candidate with cost-effective and sustainable photocatalysts.

Nanostructured TiO2 Sensitized with MoS2 Nanoflowers for Enhanced Photodegradation Efficiency toward Methyl Orange

Nanostructured titanium dioxide (TiO₂) has a potential platform for the removal of organic contaminants, but it has some limitations. To overcome these limitations, we devised a promising strategy in the present work, the heterostructures of TiO₂ sensitized by molybdenum disulfide (MoS₂) nanoflowers synthesized by the mechanochemical route and utilized as an efficient photocatalyst for methyl orange (MO) degradation. The surface of TiO₂ sensitized by MoS₂ was comprehensively characterized by X-ray diffraction (XRD), Raman spectroscopy, Fourier transform-infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), photoluminescence spectroscopy (PL), Brunauer-Emmett-Teller (BET) surface area, and thermogravimetric analysis (TGA). From XRD results, the optimized MoS₂-TiO₂ (5.0 wt %) nanocomposite showcases the lowest crystallite size of 14.79 nm than pristine TiO₂ (20 nm). The FT-IR and XPS analyses of the MoS₂-TiO₂ nanocomposite exhibit the strong interaction between MoS₂ and TiO₂. The photocatalytic results show that sensitization of TiO₂ by MoS₂ drastically enhanced the photocatalytic activity of pristine TiO₂. According to the obtained results, the optimal amount of MoS₂ loading was assumed to be 5.0 wt %, which exhibited a 21% increment of MO photodegradation efficiency compared to pristine TiO₂ under UV-vis light. The outline of the overall study describes the superior photocatalytic performance of 5.0 wt % MoS₂-TiO₂ nanocomposite which is ascribed to the delayed recombination by efficient charge transfer, high surface area, and elevated surface oxygen vacancies. The context of the obtained results designates that the sensitization of TiO₂ with MoS₂ is a very efficient nanomaterial for photocatalytic applications.

Construction of 2D layered TiO2@MoS2heterostructure for efficient adsorption and photodegradation of organic dyes

In this work, heterostructures of coupled TiO₂@MoS₂with different phases of MoS₂were synthesized via hydrothermal technique. The prepared materials were thoroughly characterized using various techniques, including XRD, SEM, transmission electron microscopy, Brunauer-Emmet-Teller, XPS, Zeta potential and UV-vis spectroscopy. The optimized nanocomposites were tested for the photocatalytic degradation of methyl Orange (MO) under visible light as well as the adsorption of Rhodamine b (RhB) and methelene blue (MB) dyes. The TiO₂@1T/2H-MoS₂heterostructures exhibited a narrow bandgap compared to the other studied nanomaterials. A remarkable photodegradation efficiency of TiO₂@1T/2H-MoS₂was observed, which completely degraded 20 ppm of MO after 60 min with high stability over four successive cycles. This can be assigned to the formation of unique heterostructures with aligned energy bands between MoS₂nanosheets and TiO₂nanobelts. The formation of these novel interfaces promoted the electron transfer and increased the separation efficiency of carriers, resulting in high photocatalytic degradation. Furthermore, the adsorption efficiency of TiO₂@1T/2H-MoS₂was unique, 20 ppm solutions of RhB and MB were removed after 1 and 2 min, respectively. The superior adsorption performance of the TiO₂@1T/2H-MoS₂can be attributed to its high surface area (279.9 m²g^-1) and the rich concentration of active sites. The kinetics and the isothermal analysis revealed that the TiO₂@1T/2H MoS₂heterstructures have maximum adsorption capacity of 1200 and 970 mg g^-1for RhB and MB, respectively. This study provides a powerful way for designing an effective photocatalyst and adsorbent TiO₂-based nanocomposites for water remediation.

Controllable growth of MoS2 nanosheets on TiO2 burst nanotubes and their photocatalytic activity

MoS2 nanosheets were grown on TiO2 nanotubes by the simple hydrothermal method for the first time. The layer-by-layer growth of MoS2 nanosheets led to a significant increase in the specific surface area of TiO2/MoS2 burst tube composites compared with TiO2 burst tubes, a significantly enhanced ability to separate photo-induced carriers, and synergistic adsorption and visible light catalytic activity of dye molecules. The maximum adsorption (q max) of MB was 72.46 mg g-1. In addition, 94.1% of MB could be degraded after 30 minutes of visible light irradiation. The microsurface morphology, structure, chemical composition, element valence and band width of TiO2/MoS2 nanocomposites were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectroscopy (DRS) and photoluminescence spectroscopy (PL). The mechanism of photocatalytic reaction was studied via free radical capture experiments.