Pure Anatase Phase Titanium Dioxide Films Prepared by Mist Chemical Vapor Deposition

Multi-Criteria Decision-Making Approach for Pre-Synthesis Selection of the Optimal Physicochemical Properties of TiO2 Photocatalytic Nanoparticles for Biomedical and Environmental Applications

Nanomaterials are widely used in several biomedical and environmental applications, due to their ideal properties. However, the synthetic and characterization procedure requires significant costs and has a negative environmental impact. Various methods are available in order to control the pre-synthesis design of the produced materials, predicting their behavior and minimizing the series of experiments. Multi-Criteria Decision-Making is proposed in this study in order to determine the best combination of the physicochemical parameters and to define the best alternative among fifteen different samples of nanostructured titanium dioxide. In particular, the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) method was applied to achieve a final ranking of the available alternatives by avoiding several of the trials that would follow testing the biological effect and the photocatalytic degradation of organic pollutants. Thus, this approach helps us to stay environmentally and ethically correct, saving time, money, and energy and also providing an optimization of the nanomaterials that are developed.

Synthesis of vacancy-rich titania particles suitable for the additive manufacturing of ceramics

In the last decades, titania (or TiO₂) particles played a crucial role in the development of photo-catalysis and better environmentally-friendly energy-harvesting techniques. In this work, we engineer a new generation of TiO₂ particles rich in oxygen vacancies using a modified sol–gel synthesis. By design, these vacancy-rich particles efficiently absorb visible light to allow carefully-controlled light-induced conversion to the anatase or rutile crystalline phases. FTIR and micro-Raman spectroscopy reveal the formation of oxygen vacancies during conversion and explain this unique laser-assisted crystallization mechanism. We achieve low-energy laser-assisted crystallization in ambient environment using a modified filament 3D printer equipped with a low-power laser printhead. Since the established high-temperature treatment necessary to convert to crystalline TiO₂ is ill-suited to additive manufacturing platforms, this work removes a major fundamental hurdle and opens whole new vistas of possibilities towards the additive manufacturing of ceramics, including carefully-engineered crystalline TiO₂ substrates with potential applications for new and better photo-catalysis, fuel cells and energy-harvesting technologies.

Green synthesis of titanium dioxide nanoparticles using plant biomass and their applications- A review

Biosynthesized nanoparticles have sparked a lot of interest as rapidly growing classes of materials for different applications. Plants are considered to be one of the most suitable sources for Green synthesis (GS) as they follow the environment-friendly route of biosynthesis of nanoparticles (NPs). This article focuses on the excavation of Titanium dioxide (TiO₂) NP from different parts of plants belonging to a distinct classification of taxonomic groups. During the process of biological synthesis of titanium NPs from plants, the extract derived from plant sources such as from root, stem, leaves, seeds, flowers, and latex possesses phytocompounds that tend to serve as both capping as well as reducing agents. TiO₂NP is one of the most commonly used engineered nanomaterials in nanotechnology-based consumer products. This article will provide an overview of the GS and characterization of TiO₂NPs from plant extracts of different taxonomic groups. Lastly, this review summarizes the current applications of TiO₂NPs.

Effect of Aluminum Doping Ratios on the Properties of Aluminum-Doped Zinc Oxide Films Deposited by Mist Chemical Vapor Deposition Method Applying for Photocatalysis

Aluminum-doped zinc oxide film was deposited on a glass substrate by mist chemical vapor deposition method. The influence of different aluminum doping ratios on the structural and optical properties of zinc oxide film was investigated. The XRD results revealed that the diffraction peak of (101) crystal plane was the dominant peak for the deposited AZO films with the Al doping ratios increasing from 1 wt % to 3 wt %. It was found that the variation of AZO film structures was strongly dependent on the Al/Zn ratios. The intertwined nanosheet structures were obtained when Zn/O ratios were greater than Al/O ratios with the deposition temperature of 400 °C. The optical transmittance of all AZO films was greater than 80% in the visible region. The AZO film deposited with Al doping ratio of 2 wt % showed the highest photocatalytic efficiency between the wavelength of 475 nm and 700 nm, with the high first-order reaction rate of 0.004 min⁻¹ under ultraviolet radiation. The mechanism of the AZO film influenced by aluminum doping ratio during mist chemical vapor deposition process was revealed.

Mist chemical vapor deposition of crystalline MoS2atomic layer films using sequential mist supply mode and its application in field-effect transistors

Molybdenum disulfide (MoS₂) mono/bilayer have been systematically investigated using atmospheric-pressure mist chemical vapor deposition (mist CVD) from (NH₄)₂MoS₄dissolved in N-methyl-2-pyrrolidone as a precursor. Film deposition was performed by alternating MoS₂mist storage within a closed chamber and mist exhaust, i.e. sequential mist supply mode at different furnace temperatures, storage times of precursor, and repetition cycles of mist supply on thermally grown SiO₂(th-SiO₂) and mist-CVD grown Al_1-xTi_xO_y(ATO) layers coated on p⁺-Si substrates. The average size of the MoS₂flake and their number of stack layers could be controlled by tuning the deposition parameters combined with substrate pretreatment. Field-effect transistors with MoS₂atomic mono/bilayer as a channel layer exhibited mobility up to 31-40 (43-55) cm²V^-1s^-1with a threshold voltage of -1.6 (-0.5) V, subthreshold slope of 0.8 (0.11) V dec.^-1, and on/off ratio of 3.2 × 10⁴(3.6 × 10⁵) onth-SiO₂(ATO) layers as gate dielectric layers without mechanical exfoliation. These findings imply that mist CVD is available for the synthesis of metal transition metal dichalcogenide and metal oxide layers as channel and gate dielectric layers, respectively.

High Temperature Stable Anatase Phase Titanium Dioxide Films Synthesized by Mist Chemical Vapor Deposition

Pure anatase-phase titanium dioxide films stable up to high temperatures were successfully fabricated by the mist chemical vapor deposition method. A post-annealing treatment of the synthesized films was carried out in oxygen atmosphere in the temperature range from 600 to 1100 °C and no anatase to rutile transformation was observed up to 1000 °C. Based on the grazing incidence X-ray diffraction data, the average crystallite size of the titanium dioxide films increased gradually with increasing annealing temperature. The structural analysis revealed that the high thermal stability of the anatase phase can be attributed to the small crystallite size and a sheet-like grain structure. An incomplete anatase to rutile transformation was observed after annealing at 1100 °C.

TiO2 Coated ZnO Nanorods by Mist Chemical Vapor Deposition for Application as Photoanodes for Dye-Sensitized Solar Cells

In this study, a mist chemical vapor deposition method was applied to create a coating of titanium dioxide particles in order to fabricate ZnO/TiO₂ core-shell nanostructures. The thin layers of titanium dioxide on the zinc oxide nanorods were uniform and confirmed as pure anatase phase. The morphological, structural, optical and photoluminescence properties of the ZnO/TiO₂ core-shell structures were influenced by coating time. For instance, the crystallinity of the titanium dioxide increased in accordance with an increase in the duration of the coating time. Additionally, the thickness of the titanium dioxide layer gradually increased with the coating time, resulting in an increased surface area. The transmittance of the arrayed ZnO/TiO₂ core-shell structures was 65% after 15 min of coating. The obtained ZnO/TiO₂ core-shell nanostructures demonstrated high potentiality to serve as photoanodes for application in dye-sensitized solar cells.