Sharif Digital Repository

Preparation of the defective TiO2 nanoparticles (NPs) have been recently in particular interest for its outstanding applications in visible-light active photocatalysis. In order to make TiO2 visible-light absorber, optical band gap should be modified especially via introducing structural defects like oxygen vacancies as an effective pathway. In this research, we prepared defective rutile TiO2 NPs with highly efficient photocatalytic activity under visible light. The NPs were synthesized by electric arc discharge in water as a cost-effective and environmentally friendly method with capability of defect formation which followed by heat treatment. The photocatalytic activity improvement... 

TiO2 is a promising photoanode material for photoelectrochemical (PEC) water splitting, but its severe bulk recombination of photogenerated carriers, sluggish oxygen evolution reaction (OER) kinetics and poor visible light response are the main bottleneck problems. Here, the carbon quantum dots (CQDs) modified anatase/rutile TiO2 photoanode (CQDs/A/R-TiO2) was designed by growth of anatase TiO2 nanothorns on rutile TiO2 nanorods and further surface modification of CQDs. The results revealed that the A/R-TiO2 heterojunction significantly suppressed the bulk recombination of photogenerated carriers. With further incorporation of CQDs into A/R-TiO2, dramatical improvement of OER kinetics and... 

The condensation process is of great importance in many heat transfer devices in which a large amount of energy must be transferred. Furthermore, condensation is a crucial part of energy conversion and affects the energy efficiency of thermal desalination plants and solar stills. During the condensation process in solar stills, an essential part of the energy is transferred through the condensation surface to produce fresh water. Therefore, the condensation surface plays a significant role in the working efficiency of solar stills. The wettability of the condensation surface influences the condensation mechanism, which, in turn, affects the efficiency of solar stills. This study aims to... 

The potential of electrospun cellulose acetate/chitosan/single walled carbon nanotubes/ferrite/titanium dioxide (CA/chitosan/SWCNT/Fe3O4/TiO2) nanofibers was investigated for the removal of Cr(VI), As(V), Methylene blue and Congo red from aqueous solutions via the adsorption and photocatalytic reduction processes. The properties of synthesized SWCNT/Fe3O4/TiO2 and fibers were characterized using TEM, SEM, FTIR, XRD, TGA and BET analysis. In adsorption process, the influence of adsorbent type including SWCNT to Fe3O4 ratio, TiO2 to SWCNT/Fe3O4 ratio and SWCNT/Fe3O4/TiO2 concentration as well as the adsorption parameters including pH, contact time, and initial concentration of adsorbates on... 

CdS/TiO2/graphene (CTG) nanocomposite thin films were synthesized by a facile production route. The TiO2/graphene (TG) nanocomposite was initially fabricated by sol-gel method in such a way that TiO2 nanoparticles loaded on graphene oxide (GO) sheet via photocatalytic process. Then, CdS nanoparticles were deposited on the TG thin film by successive ion layer adsorption and reaction process (SILAR) approach. Based on atomic force microscopy (AFM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses, the TG thin film possessed a larger surface area as compared with the pure TiO2 thin film due to presence of graphene sheet. UV/visible spectroscopy exhibited... 

BiVO4/Graphene/TiO2 as a novel nanocomposite photoanode was designed, synthesized and characterized for photoelectrochemical application. BiVO4/Graphene nanocomposite was initially synthesized by photocatalytic process and then, BiVO4/Graphene/TiO2 nanocomposite thin film was prepared by deposition of the BiVO4/Graphene solution onto the surface of sol-gel derived TiO2 thin film. Morphology, crystal structure, surface chemical composition and optical properties of the synthesized BiVO4/Graphene/TiO2 nanocomposite thin film were characterized and compared with the BiVO4/Graphene and pure TiO2 samples. Observations of scanning electron microscopy (SEM) images revealed that the surface of the... 

TiO2 thin films with mesoporous structure were deposited on quartz substrate by sol-gel dip coating. The structural, morphological and optical properties of the films were characterized by X-ray diffraction (XRD), simultaneous thermal analysis (STA), Fourier transform infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET), atomic force microscopy (AFM), transmission electron microscopy (TEM) and UV/Vis transmittance spectroscopy. Crystallization of the anatase phase was initiated at 300°C. Its transformation to the rutile phase occurred at 700°C. Anatase and rutile crystallites initially sized 3.2 and 15.3nm, respectively. The anatase phase was under tension; but the rutile phase was... 

A developed route to form TiO2 self cleaning coatings on polycarbonate substrates is reported. TiO2 coatings on plastics may find widespread application in auto and construction industries if possess desired photocatalytic and mechanical properties. A chemical surface treatment method was used to create hydrophilic groups on the surface. X-ray photoelectron spectroscopy showed the treatment led to the oxidation of surface groups. TiO2 deposition was based on wet coating using an anatase sol of TiO2 nanoparticles of 30 nm size. The sol was synthesized using a sol-gel route. A pre-coat of peroxotitanium complex was employed to improve adhesion and inhibit the substrate degradation. The coating... 

Interfacial studies and band alignment engineering on the electron transport layer (ETL) play a key role for fabrication of high-performance perovskite solar cells (PSCs). Here, an amorphous layer of SnO2 (a-SnO2) between the TiO2 ETL and the perovskite absorber is inserted and the charge transport properties of the device are studied. The double-layer structure of TiO2 compact layer (c-TiO2) and a-SnO2 ETL leads to modification of interface energetics, resulting in improved charge collection and decreased carrier recombination in PSCs. The optimized device based on a-SnO2/c-TiO2 ETL shows a maximum power conversion efficiency (PCE) of 21.4% as compared to 19.33% for c-TiO2 based device.... 

A nano-composite material consisting of amine functionalized TiO 2-coated carbon nanotubes was prepared and used for glucose oxidase (GOx) absorption. The GOx bearing nanomaterial was fixed on a glassy carbon electrode to construct a novel biosensor for glucose determination. The direct electrochemistry of immobilized GOx and its electron transfer parameters at the modified glassy carbon electrode were reported. The apparent heterogeneous electron transfer rate constant (ks) of GOx was estimated to be 3.5 s-1, which is higher than those reported previously. Amperometric detection of glucose resulted in a rapid (3 s) and stable response in the linear concentration range from 1.8 to 266 μM.... 

A modified carbon paste electrode was prepared by incorporating the TiO2 nanoparticles in the carbon paste matrix. The electrochemical behavior of gallic acid (GA) is investigated on the surface of the electrode using cyclic voltammetry and differential pulse voltammetry. The surface morphology of the prepared electrode was characterized using the scanning electron microscopy. The results indicate that the electrochemical response of GA is improved significantly at the modified electrode compared with the unmodified electrode. Furthermore, the capabilities of electron transfer on these two electrodes were also investigated by electrochemical impedance spectroscopy. Under the optimized... 

TiO2 nanostructures with different morphologies (spherical, tube, leaf-like and flower-like particles) were synthesized via a facile hydrothermal process. Polycaprolactone (PCL)/10 vol.% TiO2 nanocomposites were prepared by solvent casting methods. In vitro bioactivity of the nanocomposite films was examined by immersion in the simulated body fluid (SBF) for up to 28 days. It was found that the morphology of titania nanostructures significantly influence the in vitro bioactivity of PCL/TiO 2 nanocomposites. This observation was attributed to the amount of anatase phase and the specific surface area of the TiO2 nanostructures, which provide high surface exposure to SBF  

As a low-cost method, hydrophilic SiO2 nanoparticles (NPs) and fluid catalytic cracking (FCC) coarse particles were used as assistant materials to improve the fluidity of Al2O3 and TiO2 hard-to-fluidize nanopowders. To decrease the strong electrostatic forces between the hydrophilic nanopowders, prepared samples were fluidized in the presence of methanol vapor. Results revealed that the amount of SiO2 NPs, increased from 5 to 50 wt. %, has a beneficial effect on the fluidization quality of the binary (hard-to-fluidize NPs + SiO2) and ternary (hard-to-fluidize NPs + SiO2 + FCC) mixtures. However, the amount of FCC particles when it varied from 15 to 30 wt. % in the ternary mixtures should... 

Titanium type lithium ion-sieve nanotubes synthesized by the hydrothermal method were extensively explored over recent years due to its promising properties. However, on account of nanotubes′ tangled structure impeding the lithium adsorption in the interior nanotube walls, unalterable dimensions of the synthesized nanotubes, and a long period of annealing, the anodizing technique was proposed. It is shown that lithium uptake and adsorption capacity is improved because of easier mass transfer during the ion exchange process. This work focuses on a novel anodizing method for nanotube ion-sieve synthesis. The optimum anodizing condition was discovered by altering anodizing voltage, time, and... 

Rapid population growth and widespread industrialization are the main contributing factors to the increasing contamination of the world’s diminishing freshwater resources. This work investigates Fe/TiO2 as an efficient and sustainable photocatalyst for treating organic micropollutants in water. The photocatalysts prepared by these mechanochemical methods used a high-energy ball milling technique to manipulate Fe/TiO2’s structural, optical, and catalytic properties for the photo-oxidation of 2,4-Dichlorophenol (2,4-DCP). Doping with iron effectively reduced the band gap of rutile TiO2 from 3 to 2.22 eV. By reducing the ball/powder ratio from 34 to 7, the removal efficiency of 2,4-DCP... 

Dye sensitizers loaded on TiO2 decrease the electron excitation energy, thereby improving the photocatalytic performance by causing an increase in sensitivity under visible light irradiation. Three dye sensitizer precursors, Mordant Orange 1, N3 (red dye) and Cobalt (II) Phthalocyanine Tetrasulfonate (CoPcTs), were utilized to load the photocatalyst. The rate of the electron trapping process on platinum is clearly compatible with the migration rate of boundary electrons. Consequently, the migration of boundary electrons from the conduction band towards electron acceptors is increased by loading platinum onto the titanium dioxide. In this research, TiO2 was synthesized from a titanium... 

In this study, biocompatible ceramic layers containing TiO2 and hydroxyapatite (HA) nanoparticles (TiO2/HA) were deposited on pure commercial titanium (Grade 2) by using plasma electrolytic oxidation and AC power supply. The coating process was carried out in five different solutions for various times at a current density of 500 mA cm−2. To achieve the optimum conditions for thickness and microstructure, the coating process was conducted in solutions with a 3 g L−1 concentration of HA nanoparticles. FESEM, XRD, and FTIR results showed that HA nanoparticles were successfully incorporated into the pores of the layer. Furthermore, the corrosion behavior of the coating layers in the simulated... 

The influence of particle size and surface modification on sonocatalytic activity of TiO2 nanoparticles was investigated by measuring the degradation efficiency of methyl orange (MO) as a model pollutant. Crystalline TiO2 nanoparticles with different particles and aggregate size were prepared through solution-phase method with varying synthesis temperatures. Coating with polyvinyl alcohol was performed to enhance colloidal stability of the particles over a wide range of pH values (1.5–7.5). Characterization was carried out using X-ray diffraction, high-resolution transmission electron microscopy, dynamic light scattering, and Fourier-transformed infrared techniques. It was found that... 

In this paper, we report a promising sunlight-driven screen-printed TiO2 porous nanorods (PNR) photoanode decorated with Au plasmonic nanostructures for photoelectrochemical (PEC) light-to-electricity conversion. Fabricated photoanodes were characterized using field emission scanning electron microscopy, high-resolution transmission electron microscopy, energy dispersive spectroscopy, X-Ray diffraction analysis, X-ray photoelectron spectroscopy, N2 adsorption-desorption isotherms, UV–vis spectroscopy and electrochemical impedance spectroscopy in detail. The Au-PNR-TiO2 photoanode demonstrates superior PEC activities both under simulated sunlight and visible light irradiation. Interestingly,... 

A highly sensitive and selective sunlight-driven photoelectrochemical sensor for the direct detection and reduction of chromium(VI) was developed based on single crystal rutile titanium dioxide nanorods decorated with gold nanoparticles. Under sun simulator illumination via the amperometric technique, these Au decorated TiO2 photoelectrodes exhibited the highest sensitivity (13.94 μA μM−1) ever reported among Au-based electrodes for Cr(VI) detection, with a very low detection limit (S/N = 3) of 0.006 μM and wide linear concentration range from 0.01 μM to 50 μM. Measurements in real water samples such as laboratory and river water also showed excellent anti-interference and recovery...