Two-Functional Direct Current Sputtered Silver-Containing Titanium Dioxide Thin Films

The article reports on structure, mechanical, optical, photocatalytic and biocidal properties of Ti–Ag–O films. The Ti–Ag–O films were reactively sputter-deposited from a composed Ti/Ag target at different partial pressures of oxygen on unheated glass substrate held on floating potentialUfl. It was found that addition of ~2 at.% of Ag into TiO2film has no negative influence on UV-induced hydrophilicity of TiO2film. Thick (~1,500 nm) TiO2/Ag films containing (200) anatase phase exhibit the best hydrophilicity with water droplet contact angle (WDCA) lower than 10° after UV irradiation for 20 min. Thick (~1,500 nm) TiO2/Ag films exhibited a better UV-induced hydrophilicity compared to that of thinner (~700 nm) TiO2/Ag films. Further it was found that hydrophilic TiO2/Ag films exhibit a strong biocidal effect under both the visible light and the UV irradiation with 100% killing efficiency ofEscherichia coliATCC 10536 after UV irradiation for 20 min. Reported results show that single layer of TiO2with Ag distributed in its whole volume exhibits, after UV irradiation, simultaneously two functions: (1) excellent hydrophilicity with WDCA < 10° and (2) strong power to killE. colieven under visible light due to direct toxicity of Ag

New Insights into the Mechanism of Visible Light Photocatalysis

ABSTRACT: In recent years, the area of developing visible-lightactive photocatalysts based on titanium dioxide has been enormously investigated due to its wide range of applications in energy and environment related fields. Various strategies have been designed to efficiently utilize the solar radiation and to enhance the efficiency of photocatalytic processes. Building on the fundamental strategies to improve the visible light activity of TiO2-based photocatalysts, this Perspective aims to give an insight into many contemporary developments in the field of visible-light-active photocatalysis. Various examples of advanced TiO2 composites have been discussed in relation to their visible light induced photoconversion efficiency, dynamics of electron− hole separation, and decomposition of organic and inorganic pollutants, which suggest the critical need for further development of these types of materials for energy conversion and environmental remediation purposes

Al-pillared acid-activated montmorillonite modified electrodes

The role of acid activation of the montmorillonite matrix before pillaring and the effect of calcination temperature on the efficiency of Al-pillared acid-activated clay modified electrodes have been investigated. The electrochemical behaviour of untreated and pillared montmorillonites was compared with that of two pillared acid-activated montmorillonites. The pillared acid-activated montmorillonite modified electrodes present better electroactivity than the modified electrodes of the conventional pillared montmorillonite towards cationic and anionic redox active species. Mild acid activation of the montmorillonite matrix and a calcination temperature up to 500 °C lead to modifying materials that efficiently concentrate the cationic species. Lower calcination temperatures reverse the electrode activity. For anionic redox active species the best electroactivity was observed for pillared acid-activated montmorillonite films corresponding to a medium acid activation. In that case, a dependence of the electrochemical response on the pH was confirmed. The mechanism responsible for the observed cationic electroactivity was investigated and the behaviour of the Al-pillared acid-activated montmorillonite modified electrodes was attributed to the particular structure as well as the enhanced meso-external surface area and acidity of the clay films

Photocatalysis as an advanced reduction process (ARP): The reduction of 4-nitrophenol using titania nanotubes-ferrite nanocomposites

TiO2 photocatalysis is an advanced process, employed worldwide for the oxidation of organic compounds, that leads to significant technological applications in the fields of health and environment. The use of the photocatalytic approach in reduction reactions seems very promising and can open new horizons for green chemistry synthesis. For this purpose, titanium dioxide nanotubes (TNTs) were developed in autoclave conditions using TiO2 P25 as a precursor material. Based on these nanotubular substrates, TiO2/CoFe2O4 (TCF) nanocomposites were further obtained by wet impregnation method. The materials were thoroughly characterized and their structural, textural, vibrational, optoelectronic and magnetic properties were determined. The composite materials combine absorbance in the visible optical range and high BET surface area values (˜100 m2/g), showing extremely high yield in the photocatalytic reduction of 4-nitrophenol (4-NP), exceeding 94% within short illumination time (only 35 min). The developed nanocomposites were successfully reused in consecutive photocatalytic experiments and were easily removed from the reaction medium using magnets. Both remarkable recycling ability and high-performance stability in the photocatalytic reduction of nitrophenol were observed, thus justifying the significant economic potential and industrial perspectives for this advanced reduction process. © 2018 Elsevier B.V

Preparation of Nd-Fe-B Magnets by Screen Printing

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Magnetically separable TiO2/CoFe2O4/Ag nanocomposites for the photocatalytic reduction of hexavalent chromium pollutant under UV and artificial solar light

In this work, novel ternary catalysts Ag/TiO2/CoFe2O4 were synthesized with variable ferrite content for the photocatalytic reduction of Cr+6 pollutant, under UV and solar light illumination. Both TiO2 (T) and CoFe2O4 (CF) were synthesized using the sol-gel method followed by hydrothermal treatment to prepare the TiO2/CoFe2O4 (TCF) composite. Silver nanoparticles were successfully loaded on the surface of TCF to get different Ag/TCF composites. The analysis of their crystal structure indicated the presence of pure anatase phase TiO2, cubic CoFe2O4, and silver nanoparticles, in both XRD patterns and Raman spectra. It was found that the addition of silver nanoparticles to the titania/ferrite composite has a great contribution to the photocatalytic reduction of Cr+6 species. The photocatalytic reaction mechanism was studied by applying scavenging reaction process and spin trap experiments, revealing that photogenerated electrons were mainly responsible for the reduction of Cr+6 species. After the photocatalytic experiments, the composite catalyst can be easily separated from the reaction solution with a magnetic bar and be re-used. © 2019 Elsevier B.V

Inorganic-organic core-shell titania nanoparticles for efficient visible light activated photocatalysis

a b s t r a c t Nanostructured modified TiO 2 (m-TiO 2 ) was synthesized using the gel combustion method based on the calcination of an acidified alkoxide solution mixed with urea. The materials were characterized by Raman, FT-IR and UV-vis diffuse reflectance spectroscopies, transmission (TEM) and scanning electron microscopies (SEM), X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR), in comparison with reference material untreated with urea (ref-TiO 2 ). The effect of both the urea content and calcination temperature were optimized, providing the optimal absorption threshold of 2.19 eV for solar light harvesting. The photocatalytic performance of the m-TiO 2 powder was tested for the degradation of methylene blue (MB) azo dye under UVA (350-365 nm), visible (440-460 nm), and daylight (350-750 nm) illumination. The hybrid inorganic/organic material shows exceptional physicochemical properties and significant photocatalytic activity, especially in the visible, attributed to sensitization of the TiO 2 by a thin porous layer of carbonacious species in controlled core-shell morphology