Advances in Metal-based Vanadate Compound Photocatalysts: Synthesis, Properties and Applications

Among the ongoing research on photocatalysis under visible-light, it has been shown that doped or hybrid catalysts are more active than a single catalyst alone. However, problems including visible light absorption, a low quantity of energetic sites on surfaces, and rapid recombination of the photo-electron hole pair produced by light have prohibited photocatalysts from being used in a practical and widespread manner. To overcome these problems, synthesis of nanostructure hybrid catalyst using several methods has attracted much attention. Several procedures have been suggested for the preparation of photocatalysts with the desired structure and morphology. Preparation methods similar to partial modification may lead to diverse structures and qualities. In this regard, the development of efficient, low-cost photocatalysts and rapid synthesis is the most important issues that should be considered. This review discusses various methods and mechanisms that work with the modification of vanadium compounds as photocatalysts to progress their photocatalytic efficiency. In addition, the effects of synthesis temperature, solution pH and concentration on the photocatalytic performance are also described in detail

The effect of Fe in the rapid thermal explosion synthesis and the high-temperature corrosion behavior of porous Co-Al-Fe intermetallic

High porosity Co-Al-Fe intermetallic with 3D-microstructures were one-step synthesized via a novel thermal explosion reaction. A link between pore structure and permeability was established using 3D-XRM technology. The corrosion resistance of the samples with different Fe contents was investigated at 900 °C under an oxygen/sulphur atmosphere for up to 120 h. The results showed that the pore structure of the samples remains stable, and the internal matrices are intact due to the formation of a thin protective layer of Al2O3 and Fe2O3 on the surface of the product skeleton. In addition, inward diffusion of S leads to the formation of FeS nodules

A Review on Sustainable Manufacturing of Ceramic-Based Thin Films by Chemical Vapor Deposition (CVD): Reactions Kinetics and the Deposition Mechanisms

Chemical vapor deposition (CVD) is a process that a solid is formed on a substrate by the chemical reaction in the vapor phase. Employing this technology, a wide range of materials, including ceramic nanocomposite coatings, dielectrics, and single crystalline silicon materials, can be coated on a variety of substrates. Among the factors influencing the design of a CVD system are the dimensions or geometry of the substrate, substrate temperature, chemical composition of the substrate, type of the deposition process, the temperature within the chamber, purity of the target material, and the economics of the production. Three major phenomena of surface reaction (kinetic), diffusion or mass transfer reaction, and desorption reaction are involved during the CVD process. Thermodynamically, CVD technology requires high temperatures and low pressures in most systems. Under such conditions, the Gibbs free energy of the chemical system quickly reaches its lowest value, resulting in the production of solids. The kinetic control of the CVD technology should always be used at low temperatures, and the diffusion control should be done at high temperatures. The coating in the CVD technology is deposited in the temperature range of 900–1400 °C. Overall, it is shown here that by controlling the temperature of the chamber and the purity of the precursors, together with the control of the flow rate of the precursors into the chamber, it is possible to partially control the deposition rate and the microstructure of the ceramic coatings during the CVD process

Scalable fabrication of tunable titanium nanotubes via sonoelectrochemical process for biomedical applications.

Titanium does not react well with the human tissues and due to its bio-inert nature the surface modification has yet to be well-studied. In this study, the sonoelectrochemical process has been carried out to generate TiO2 nanotube arrays on implantable Ti 6-4. All the prepared nanotubes fill with the vancomycin by immersion and electrophoresis method. Drug-releasing properties, antibacterial behavior, protein adsorption and cell attachment of drug-modified nanotubes are examined by UV-vis, flow cytometry, modified disc diffusion, BSA adsorption, and FESEM, respectively. The most uniform morphology, appropriate drug release, cell viability behavior and antibacterial properties can be achieved by samples anodized in the range of 60-75 V. Also improves the adsorption of BSA protein in bone healing and promotes osteoblast activity and osseointegration. Drug loading efficiency increases up to 60% via electrophoresis comparing the immersion method for anodized sample in 75 V. While electrophoresis does not affect the amount of vancomycin adsorption for lower voltages. Besides, the present study indicates that an anodized sample without drug loading has no antibacterial activity. Moreover, 28-days drug releasing from nanotubes is investigated by mathematical formula according to Fickian's law to find an effective dose of loaded drug