Hemraj M. Yadav

Developments in photocatalytic antibacterial activity of nano TiO2: A review

TiO2, which is one of the most explored materials, has emerged as an excellent photocatalyst material for environmental and energy fields, including air and water purification, self-cleaning surfaces, antibacterial and water splitting. This review summarizes recent research developments of TiO2-based photocatalyst used for photocatalytic antibacterial applications. Several strategies to enhance the efficiency of TiO2 photocatalyst are discussed, including doping with metal ions, noble metals, non-metals, and coupling with other materials. The mechanism of photocatalytic antibacterial activity in the presence of nano-sized TiO2 is also discussed. The modified TiO2 photocatalyst significantly inhibits the growth of bacterial cells in response to visible light illumination. TiO2 photocatalysis appears to be promising as a route of advanced oxidation process for environmental remediation.

One-step synthesis of uniform and biocompatible amine functionalized cobalt ferrite nanoparticles: a potential carrier for biomedical applications

For the first time a simple one step method has been developed for the synthesis of uniform, water dispersible, amine functionalized nanoparticles of size about 7 nm. The synthesis process was accomplished by refluxing Fe(acac)3 and Co(acac)2 in diethylene glycol and ethanolamine. The synthesized particles show superparamagnetism at room temperature. Amine functionalized nanoparticles exhibit good cell viability, which is above 94% at a concentration of 80 μg mL−1 in MCF7 and L929 cell lines. The bare and functionalized cobalt ferrite nanoparticles were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) techniques. Their magnetic properties were also studied by using a superconducting quantum interference device (SQUID) technique. The presence of surface amine groups, good aqueous dispersion stability and excellent biocompatibility make them a suitable candidate for biomedical applications.

Enhanced visible light photocatalytic activity of Cr3+-doped anatase TiO2 nanoparticles synthesized by sol–gel method

Abstract The photocatalytic degradation of methylene blue (MB) has been investigated under visible light irradiation with an incandescent light bulb using chromium doped TiO2 nanoparticles. Cr–TiO2 photocatalysts were successfully synthesized by sol–gel method at room temperature and characterized by X-ray diffraction (XRD), UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS), Raman spectroscopy, Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy. The band gap energy of the nanoparticles were estimated using UV–Vis DRS technique. With increasing Cr3+ cations content into TiO2 host lattice, the optical absorption band tuned in the visible region. XRD and TEM results reveal uniform and crystalline anatase TiO2 nanoparticles. The photodegradation of MB indicated that the photocatalytic activity of pure TiO2 nanoparticles increased with increasing Cr3+ cations concentration.

Multilayer thin film deposition of Pd/Ag alloy as an application for hydrogen sensing

A highly sensitive H2 gas sensor was fabricated using a microelectromechanical system (MEMS) procedure having an embedded micro-heater. The palladium-silver (Pd/Ag having stoichiometric ratios 77:23) thin film was deposited by the RF/DC magnetron sputtering and used as the hydrogen sensing layer designed as a zig-zag pattern. The working temperature of the micro heater showed a linear relation with variations of the heater voltage. The electrothermal properties of the H2 sensor were studied by finite element method (FEM). The sensing properties of the fabricated H2 sensor as the change of electrical resistance were studied with respect to hydrogen concentration and temperature. Experimental results showed high sensitivity and response time after application of the heater voltage. The sensing properties of the alloyed Pd/Ag thin film were more improved than those of pure palladium. The maximum sensitivity (Rs) of the fabricated H2 sensor was 14.26% for 1000 ppm H2. The gas sensitivity of the fabricated H2 sensor showed linear behavior with the heater voltage (operating temperature) and positively corresponded with the hydrogen concentration.

Visible Light Photocatalytic Performance of In Situ Synthesized Graphite-SiO2–TiO2 Composite Towards Degradation of Benzene Gas

Graphite-SiO2-TiO2 composites with optimum graphite and SiO2 loadings were prepared by a facile one-pot chemical route. The structural, morphological and physiochemical properties of the samples were investigated by analytical techniques. UV-Vis-DRS analysis confirmed light absorbance edge of composites was sharply red-shifted to the visible region with increasing graphite and SiO2 content. The prepared composites showed higher photocatalytic activity towards degradation of benzene gas under visible light. The contribution of graphite and SiO2 on the enchantment of visible light photocatalytic performance of the composites was discussed.

Fabrication of SiO2/TiO2 double layer thin films with self-cleaning and photocatalytic properties

Transparent antireflective SiO2/TiO2 double layer thin films were prepared using a sol–gel method and deposited on glass substrate by spin coating technique. Thin films were characterized using XRD, FE-SEM, AFM, UV–Vis spectroscopy and water contact angle measurements. XRD analysis reveals that the existence of pure anatase phase TiO2 crystallites in the thin films. FE-SEM analysis confirms the homogeneous dispersion of TiO2 on SiO2 layer. Water contact angle on the thin films was measured by a contact angle analyzer under UV light irradiation. The photocatalytic performance of the TiO2 and SiO2/TiO2 thin films was studied by the degradation of methylene blue under UV irradiation. The effect of an intermediate SiO2 layer on the photocatalytic performance of TiO2 thin films was examined. SiO2/TiO2 double layer thin films showed enhanced photocatalytic activity towards methylene blue dye.

Self-Cleaning and Photocatalytic Performance of TiO2 Coating Films Prepared by Peroxo Titanic Acid

Self-cleaning and photocatalytic TiO2 thin films were prepared by a facile sol-gel method followed by spin coating using peroxo titanic acid as a precursor. The as-prepared thin films were heated at low temperature(110 °C) and high temperature (400 °C). Thin films were characterized by X-ray diffraction(XRD), Field-emission scanning electron microscopy(FESEM), UVVisible spectroscopy and water contact angle measurement. XRD analysis confirms the low crystallinity of thin films prepared at low temperature, while crystalline anatase phase was found the for high temperature thin film. The photocatalytic activity of thin films was studied by the photocatalytic degradation of methylene blue dye solution. Self-cleaning and photocatalytic performance of both low and high temperature thin films were compared.

Multifunctional Magnetic Nanostructures for Cancer Hyperthermia Therapy

Current treatments for various types of cancers can be headed under chemotherapy, radiotherapy, and tumor extirpation. These approaches have the potential to save lives; but they fail to exterminate the disease. Additionally, the unavoidable side effects of these treatments make a patient’s life insufferable. Attempts should be made for better kinds of treatments that improve a patient’s quality of life. Toward this end, local treatment of tumors by heating them at high temperatures could be successful. Exposing tumors for hyperthermic effect using magnetic nanoparticles is a relatively new method used for cancer therapy. Magnetic nanoparticles (MNPs) are inserted into the bloodstream so that they bind to the cancerous cells and possibly kill them by increasing their temperature to about 40–46°C. The underlying principle behind this kind of treatment is that an alternating magnetic field is applied, which generates heat by different heat loss mechanisms so the generated heat destroys the cancer cells.