The photocatalytic, sonolytic and sonophotocatalytic degradation of 4-chloro-2-nitrophenol (4C2NP) using heterogeneous (TiO2) was investigated in this study. Experiments were performed in slurry mode with artificial UV 125 watt medium pressure mercury lamp coupled with ultrasound (100 W, 33+3 KHz) for sonication of the slurry. The degradation of compound was studied in terms of first order kinetics. The catalyst concentration was optimized at 1.5 gL-1, pH at 7 and oxidant concentration at 1.5 gL-1. The results obtained were quite appreciable as 80% degradation was obtained for photocatalytic treatment in 120 minutes whereas, ultrasound imparting synergistic effect as degradation achieved 96% increase in 90 minutes during sonophotocatalysis. The degradation follows the trend sonophotocatalysis > photocatalysis > sonocatalytic > sonolysis. The results of sonophotocatalytic degradation of pharmaceutical compound showed that it could be used as efficient and environmentally friendly technique for the complete degradation of recalcitrant organic pollutants which will increase the chances for the reuse of wastewater.

In this work, three ceramic composite coatings Al2O3-3TiO2 C, Al2O3-13TiO2 C, and Al2O3-13TiO2 N were plasma sprayed on steel substrates. They were deposited with two conventional powders differing the volume fraction of TiO2 and nanostructured powder. The mechanical and tribological properties of the coatings were investigated and compared. The increase in TiO2 content from 3 wt.% to 13 wt.% in the conventional feedstock improved the mechanical properties and abrasion resistance of coatings. However, the size of the used powder grains had a much stronger influence on the properties of deposited coatings than the content of the titania phase. The Al2O3-13TiO2 coating obtained from nanostructured powder revealed significantly better properties than that plasma sprayed using conventional powder, i.e. 22% higher microhardness, 19% lower friction coefficient, and over twice as good abrasive wear resistance. In turn, the Al2O3-13TiO2 conventional coating showed an increase in microhardness and abrasive wear resistance, 36% and 43%, respectively, and 6% higher coefficient of friction compared to the Al2O3-3TiO2 conventional coating.

In this work, a design equation was presented for a batch-recirculated photoreactor composed of a packed bed reactor (PBR) with immobilised TiO2-P25 nanoparticle thin films on glass beads, and a continuous-flow stirred tank (CFST). The photoreactor was studied in order to remove C.I. Acid Orange 7 (AO7), a monoazo anionic dye from textile industry, by means of UV/TiO2 process. The effect of different operational parameters such as the initial concentration of contaminant, the volume of solution in CFST, the volumetric flow rate of liquid, and the power of light source in the removal efficiency were examined. A rate equation for the removal of AO7 is obtained by mathematical kinetic modelling. The results of reaction kinetic analysis indicate the conformity of removal kinetics with Langmuir-Hinshelwood model (kL-H = 0.74 mg L-1 min-1, Kads = 0.081 mg-1 L). The represented design equation obtained from mathematical kinetic modelling can properly predict the removal rate constant of the contaminant under different operational conditions (R2 = 0.963). Thus the calculated and experimental results are in good agreement with each other.

The present work concerns analysis of the possibilities of synthesis of Ni-TiO2 composite coatings from electrolytes containing formate nickel complexes. A magnetic field was applied as an additional factor enabling modification of properties of the synthesized coatings through its influence on electrode processes. The presented data describes the effect of electrode potential, TiO2 concentration in the electrolyte as well as the value of the magnetic field induction vector on the deposition rate, composition, current efficiency, structure, surface states and morphology of synthesized coatings. The studies were preceded by thermodynamic analysis of the electrolyte. The obtained results indicated possibilities of synthesis of composites containing up to 0.97 wt. % of TiO2. Depending on applied electrolysis conditions current efficiency amounted to from 61.2 to 75.1%.

In this paper an analysis of the surface properties of (Ti,Pd,Eu)O_x thin films prepared by magnetron sputtering has been described. In particular, the results of composition and structure investigations were studied in relation to the surface state and optical properties. It was found that (Ti,Pd,Eu)O_x film was nanocrystalline and had a rutile structure. The average crystallites size was equal to 7.8 nm. Films were homogeneous and had densely packed grains. Investigation of the surface properties by XPS showed that titanium was present at 4+ state (in the TiO₂form), palladium occurred as PdO₂(also at 4+ state), while europium was in Eu₂O₃form (at 3+ state). In comparison with the unmodiffied TiO₂, the coating with Pd and Eu additives had a rather high transparency (approx. 47%) in the visible light range, its optical absorption edge was shifted towards into the longer wavelengths (from 345 nm to 452 nm), and the width of optical energy gap Egopt was nearly twice lower (1.82 eV). Besides, the resistivity of (Ti,Pd,Eu)O_x at room temperature was 1×10³ Wcm. In the case of the film as-deposited on Si substrate (p-type) the generation of photocurrent as a response to light beam excitation (λ_exc = 527 nm) was observed.

There is a high impact of the solar cells on energy manufacturing. For several years the energy efficiency was limited due to base-materials' structural and technological limits. High increase of energy harvesting of solar cells has been observed since the first solar cell based on dye-sensitized colloidal TiO₂ films occurred. One of the most promising solutions are used quantum dots (QD) for light energy conversion. In this paper, we described the use of selected characterization techniques for sandwich-type TiO₂/QD composites for a low-cost quantum dots' solar cell in the point of view of mass manufacturer of solar cells and research and development laboratory. Moreover, the increasing role of Raman spectroscopy and mapping for the TiO₂/QD was presented and compared with other necessity techniques for solar cell investigations such as ellipsometry, atomic force microscopy (AFM), and secondary ion mass spectrometry (SIMS).

In the present work TiO₂ nanoparticles (NPs) have been dispersed into three different nematic liquid crystals (2020, 1823A and 1550C) in different concentration. The value of the birefringence (Δn) has been calculated by the transmitted intensity method at a 632.8 nm wavelength. NLC 2020 used in the present study is a high birefringent material (Δn = 0.44), NLC 1550C is a low birefringent material (Δn = 0.067) and NLC 1823A is a mid birefringent material (Δn = 0.14). An increased value of birefringence has been found after dispersion of TiO₂ NPs in all three NLCs but this increment depends upon the concentration of the dopant material, temperature range and chemical character of the mixtures. It is suggested that this LC materials can be applicable in making of phase shifters, compensators and many more photonic devices.

Recently, transition metal oxides, which exhibit favorable catalytic abilities, have also been investigated as a material for the detection of hydrazine (N2H4). It has been reported that mixed metal oxides usually offer a higher electrochemical activity than binary oxides. In this work, a TiO2–Fe2O3 coupled system is presented as an enhanced material with major applications in electrochemical detectors. The electrochemical behavior of glassy carbon electrodes modified with TiO2–Fe2O3 in the absence and presence of hydrazine was evaluated via cyclic voltammetry (CV). Experimental results also suggest that the formation of the TiO2– Fe2O3 coupled system enhances electrochemical catalytic performance in N2H4 detection. The modification TiO2 + 2 mol% Fe2O3 provides good analytical performance of detection (0.13 mM) and quantification limits (0.39 mM). The presented coupled system provides the premise for a suitable material for a stable and sensitive N2H4 sensor.

Alternating current a.c. measurements enable to understand the physical and chemical processes occurring in semiconductor materials. Impedance spectroscopy has been successfully applied to study the responses of gas sensors based on metal oxides, such as TiO2, SnO2 and TiO2/SnO2 nanocomposites. This work is devoted to dynamic measurements of hydrogen sensor behaviour over the temperature range of 300–450◦C. Frequency dependence of the impedance signal gives evidence that 50 mol% TiO2/50 mol% SnO2 nanocomposites should be treated as resistive-type sensors. Temporal evolution of the response to 500 ppm H2 at 320◦C indicates a very short response time and much longer recovery.

The mechanical properties of cement paste modified by nano-TiO2 (nT) and nano-SiO2 (nS) were experimentally studied. The compressive strength increased first and then decreased with the increase of nanoparticle content. When nanoparticles were added into the cement paste as a filler to improve the microstructure, the two kinds of particles both could form a tighter mesh structure, which would enhance the density and strength of the structure. The elastic modulus increased rapidly with the increase of the nT content and reached a peak when the nanoparticle content is about 3%, which was about twice the elastic modulus of ordinary cement paste. The Scanning electron microscopy (SEM) observation results showed that the microstructure of cement was network connection and fiber tube. The hydration progress of ordinary cement slurry was insufficient, and many unreacted cement particles remained. With the addition of nanoparticles, the internal structure of the cement became denser, with fewer pore cracks, smaller pore diameters, more complex fiber tube arrangements, and significant anisotropy, thereby improving strength and mechanical properties.