Nanotechnology is a fast-expanding area with a wide range of applications in science, engineering, health, pharmacy, and other fields. Nanoparticles (NPs) are frequently prepared via a variety of physical and chemical processes. Simpler, sustainable, and cost-effective green synthesis technologies have recently been developed. The synthesis of titanium dioxide nanoparticles (TiO₂ NPs) in a green/sustainable manner has gotten a lot of interest in the previous quarter. Bioactive components present in organisms such as plants and bacteria facilitate the bio-reduction and capping processes. The biogenic synthesis of TiO₂ NPs, as well as the different synthesis methods and mechanistic perspectives, are discussed in this review. A range of natural reducing agents including proteins, enzymes, phytochemicals, and others, are involved in the synthesis of TiO₂ NPs. The physics of antibacterial and photocatalysis applications were also thoroughly discussed. Finally, we provide an overview of current research and future concerns in biologically mediated TiO₂ nanostructures-based feasible platforms for industrial applications.

TiO₂ nanoribbons (TiO₂ NRs) loaded with FeCo-Al₂O₃ catalyst were synthesized and used as a precursor in the synthesis of TiO₂ nanoribbons/carbon nanotubes (TiO₂ NRs/CNTs) composite by a chemical vapor deposition (CVD) method. TiO₂ NRs and TiO₂ NRs/CNTs composite were characterized by XRD, FT-IR, TEM, SEM, EDX and UV-Vis spectrophotometer. The results revealed the formation of TiO₂-B and hydrogen titanate nanoribbon like structures by the hydrothermal treatment. After loading TiO₂ NRs by FeCo-Al₂O₃ catalyst and the CVD growth of carbon nanotubes, the synthetic TiO₂ nanoribbons converted entirely to TiO₂-B nanoribbons with nanopits structure. The composite composed of tube-like nanostructures forming an interlocked network from CNTs and TiO₂-B NRs. The composite shows a relatively red-shifted band gap (3.09 eV), broader and stronger UV absorption band relative to TiO₂ NRs. The photocatalytic properties of TiO₂ NRs and TiO₂ NRs/CNTs composite were studied under sunlight irradiation. The photocatalytic degradation of methylene blue (MB) dye was investigated as a function of contact time, dye concentration, and catalyst dose. The kinetics and mechanisms of degradation were discussed. TiO₂ NRs/CNTs composite showed higher stability after six runs and 50% shorter irradiation time than TiO₂ NRs photocatalyst.

In this report, the structures, morphologies, optical, electrical and gas sensing properties of ZnO and ZnO: Na spin-coated films are studied. X-ray diffraction (XRD) results reveal that the films are of a single phase wurtzite ZnO with a preferential orientation along (002) direction parallel to c-axis. Na doping reduces the crystalline quality of the films. The plane surface of ZnO film turned to be wrinkle net-work structure after doping. The reflectance and the optical band gap of the ZnO film decreased after Na doping. The wrinkle net-work nanostructured Na-doped film shows an unusually sensitivity, 81.9% @ 50 sccm, for CO₂ gas at room temperature compared to 1.0% for the pure ZnO film. The signals to noise ratio (SNR) and detection limit of Na-doped ZnO sensor are 0.24 and 0.42 sccm, respectively. These enhanced sensing properties are ascribed to high surface-to-volume ratio, hoping effect, and the increase of O- vacancies density according to Kroger VinK effect. The response time increased from 179 to 240 s by the incorporation of Na atoms @50 sccm. This response time increased as the CO₂ concentration increased. The recovery time is increased from 122 to 472 s by the incorporation of Na atoms @50 sccm.

Dirt and microorganisms are the major problems in textiles which can generate unpleasant odor during their growth. Here, zinc oxide (ZnO) nanoparticles prepared by sol-gel method were loaded on the cotton fabrics using spin coating technique to enhance their antimicrobial properties and water repellency. The effects of ZnO precursor concentration, precursor solution pH, number of coating runs, and Mg doping percent on the structures, morphologies, and water contact angles (WCA) of the ZnO-coated fabrics were addressed. At 0.5 M concentration and pH7, more homogeneous and smaller ZnO nanoparticles were grown along the preferred (0 0 2) direction and uniformly distributed on the fabric with a crystallite size 17.98 nm and dislocation density 3.09 × 10⁻³ dislocation/nm². The substitution of Zn ²⁺ with Mg ²⁺ ions slightly shifted the (002) peak position to a higher angle. Also, the zeta potential and particle size distribution were measured for ZnO nanoparticle suspension. A superhydrophobic WCA = 154° was measured for the fabric that coated at 0.5 M precursor solution, pH 7, 20 runs and 0% Mg doping. Moreover, the antibacterial activities of the ZnO-coated fabric were investigated against some gram-positive and gram-negative bacteria such as Salmonella typhimurium, Klebsiella pneumonia, Escherichia coli, and Bacillus subtilis.