Nanostructured TiO2 Thin Films Research Articles

Modification of the optical properties and nano-crystallinity of anatase TiO2nanoparticles thin film using low pressure O2 plasma treatment

TiO2 nanoparticles (NPs) thin films with a thickness of 50 nm and a core-shell nanostructure were prepared using the spin coating technique and were treated using an inductively coupled O2 plasma at low pressure. While no significant features were observed during pumping, two kinetics can be identified during plasma processing using in situ spectroscopic ellipsometry. For very short plasma treatment times, the removal of solvent-based organic moieties surrounding TiO2 nanoparticles produces a densification of the inorganic TiO2 films. Such mineralization effect by the O2 plasma treatment was confirmed by X-ray photoelectron microscopy. For larger time scales, the average size of TiO2 NPs rises and significant changes of the optical properties occur. While no significant changes in the film nanostructure were observed by Scanning Electron Microscopy, a rise in the crystallite size and an increase in the agglomeration of TiO2 nanoparticles were confirmed by Transmission Electron Microscopy and Atomic Force Microscopy, respectively. The mechanisms involved in such plasma-induced modification of nanostructured TiO2 thin films are discussed in line with the energy fluxes of plasma-generated species.

Visible light sensitization of TiO2/Ag/N nanostructures synthesized by microwave irradiation for oxidative degradation of organic dyes

The synthesis of photocatalysts for organic pollutants degradation is a topic of fundamental interest and practical importance, in particular if using green methodologies. In this study, Methyl Orange (MO) and Indigo Carmine (IC) photodegradation on composite TiO2 nanostructures containing silver or nitrogen was examined. TiO2 nanotubes (NTs), TiO2 nanoparticles (NPs) and Ag NPs were prepared by microwave-assisted chemistry (MWAC) using different precursors. The photocatalysts were characterized by XRD, TEM, UV–Vis, BET, XPS and EIS techniques. The degradation rate of MO by the TiO2 NTs@Ag NPs photocatalyst, under UV–Vis illumination, was about six times higher than that exhibited by the pristine TiO2 NTs. Additionally, the photodegradation rate of MO on TiO2 NTs@Ag NPs under visible light (λ ≥ 400 nm) was more than three times higher than pristine TiO2 NTs irradiated with UV–Vis light. TiO2 NPs prepared using a water-soluble titanium complex [TALH: Titanium(IV) bis(ammoniumlactato)dihydroxide] as precursor, presents high photodegradation rate for IC and MO under UV–Vis and only visible light irradiation. The presence of nitrogen in the TiO2 NPs lead to lower band gap values, compared to pristine NTs, which may explain the visible light activity of this photocatalyst. Additionally, Mott–Schottky analysis gave information about the donor density and the absolute position of the flatband potential of the nanostructured TiO2 thin film electrodes showing a correlation between those parameters and the photocatalytic observed activity. The present work also shows that a green methodology, such as MWAC, coupled to a mild water-soluble precursor, like TALH, may lead to its use in environmental remediation applications with direct utilization of solar light as a sustainable technology.

Substrate Temperature Dependence of TiO2 Films Deposited by Spray Ultrasonic Nebulizer Technique

This work details the growth of nanostructured TiO2 thin films on a glass substrates using the ultrasonic nebulizer technique, deposited at 300-600 °C . The influence of the deposition temperature is linked to the physic-chemical properties of the TiO2 thin films. XRD- results confirmed that the nanostructures tetragonal are polycrystalline, the grain size(s) increases alongside the substrates temperature, and the deposited film is the anatase phase at 400 C. The surface morphology of the deposited film were imaged using the (AFM) technique, and it was confirmed that the films are of excellent crystallinity and are homogeneously dispersed. It was also confirmed that the Root Mean Square (RMS) of the thin films' surface roughness is dictated by the substrate's temperature, which was further confirmed using the SEM technique. The substrate temperature is inversely proportional to the optical energy gap values. The increase in optical gap with increasing substrate temperature can be due to improvement in the films crystallinity .At higher temperatures promote a high mobility of ad-atoms; it allows a better atomic arrangement, which promotes the formation of a crystalline structure.

ZnO@TiO2 Core Shell Nanorod Arrays with Tailored Structural, Electrical, and Optical Properties for Photovoltaic Application.

ZnO has prominent electron transport and optical properties, beneficial for photovoltaic application, but its surface is prone to the formation of defects. To overcome this problem, we deposited nanostructured TiO2 thin film on ZnO nanorods to form a stable shell. ZnO nanorods synthesized by wet-chemistry are single crystals. Three different procedures for deposition of TiO2 were applied. The influence of preparation methods and parameters on the structure, morphology, electrical and optical properties were studied. Nanostructured TiO2 shells show different morphologies dependent on deposition methods: (1) separated nanoparticles (by pulsed laser deposition (PLD) in Ar), (2) a layer with nonhomogeneous thickness (by PLD in vacuum or DC reactive magnetron sputtering), and (3) a homogenous thin layer along the nanorods (by chemical deposition). Based on the structural study, we chose the preparation parameters to obtain an anatase structure of the TiO2 shell. Impedance spectroscopy shows pure electron conductivity that was considerably better in all the ZnO@TiO2 than in bare ZnO nanorods or TiO2 layers. The best conductivity among the studied samples and the lowest activation energy was observed for the sample with a chemically deposited TiO2 shell. Higher transparency in the visible part of spectrum was achieved for the sample with a homogenous TiO2 layer along the nanorods, then in the samples with a layer of varying thickness.

Time-Dependent Photoluminescence of Nanostructured Anatase TiO2 and the Role of Bulk and Surface Processes

TiO2 is one of the most attractive photocatalysts, with applications in water splitting, wastewater treatment, and air purification. Understanding the fundamentals of the functioning of TiO2 requires knowledge of the nature and dynamics of photo-induced excitons and charge carriers. Although photoluminescence (PL) spectroscopy can provide important fundamental insights, photophysical mechanisms are still under debate. To address this problem, the aim of the present work is to investigate the evolution of the PL spectrum in time of nanostructured anatase TiO2 thin films and the nature of associated processes, at room temperature and in aqueous media closely resembling photocatalytic conditions. We show that the PL spectrum of commonly used nanostructured anatase TiO2 thin films in aqueous media is time-dependent, with pH-dependent broadening at the low energy side of the spectrum in time. By global analysis of the spectrotemporal PL behavior and the effect of addition of NaCl at neutral and mildly acidic conditions, we show that this spectral development is due to an increasing contribution of processes sensitive to surface termination relative to bulk processes to the PL in time. The time-dependent PL spectrum and dynamics can be assigned to the recombination of mobile electrons populating the conduction band or shallow traps with immobile hole polarons in deep traps and motion of electrons from the nanoparticle bulk toward the depletion layer/surface in ca. 1 ns. This directionality likely plays an important role in the photocatalytic performance of nanostructured anatase TiO2 and effects of ions such as chloride in aqueous media. Control of the directional motion of electrons and suppression of surface charge recombination via surface engineering show promise to further increase the photocatalytic activity.

The structural, optical and photocatalytic properties of the TiO2 thin films

Nanostructured TiO2 thin films were prepared by sol-gel method on the glass substrates and annealed at various temperatures in air atmosphere. The structural and optical properties have been studied as a function of the annealing temperature. XRD diffraction spectra reveals that the anatase phase transformed into orthorhombic brookite phase when annealing at the temperature of 600 °C. SEM and AFM images indicate that grain size and average roughness of the films were increased with the increasing of annealing temperature. In contrast, the optical band gap was decreased with increasing of the annealing temperature. Moreover, anatase phase TiO2 thin film has the best photocatalytic activity compared to amorphous and brookite TiO2 thin films and kept the high degradation rate in all cycling experiments.

Effect of noble metal functionalization and film thickness on sensing properties of sprayed TiO2 ultra-thin films

In this paper, the effect of the thickness of nano-structured TiO2 thin films (12–40 nm) and successive deposition of different noble metal nanoparticles on the performances of propanol vapor and H2 gas sensors was investigated. The obtained titania thin films were integrated into a device for UV, gas, and gas/vapor sensing studies at different operating temperatures. Qualitative analysis revealed that the sensor selectivity and its response could be altered by film thickness and type of noble metal nanoparticles. The results indicate that the sensor with 40 nm TiO2 film has the highest response to H2 gas (˜ 650%). The fastest response time and the most rapid recovery however were achieved by the sensors made of 12 nm sprayed TiO2 ultra-thin films, which also offered the highest selectivity to H2 gas.The best UV detection performances were demonstrated by films functionalized with Au nanoparticles (the IUV/Idark ≈ 80). The structural, chemical, electrical, UV, and gas sensing properties of such films were investigated using SEM, AFM, Raman spectroscopy, electrical characterization, and sensing experiments. It has been clearly demonstrated that films are nanostructured and have mixed phases that contain mostly anatase (annealed at 450 °C) and small amounts of rutile after thermal annealing at higher temperatures (more than 600 °C), as improved materials for sensor applications. Our combined study analyzes the relationship between thickness, electrical properties and the gas/vapor sensing performance of such thin film based TiO2 gas sensors as well as the effect of different types of noble metal nanoparticles (Au, Ag, Ag-Au and Ag-Pt) deposited on the surface. The enhanced response was attributed to the involvement of noble nanoalloy or nanoparticle interface to titania forming nano-junctions in the gas sensing mechanism. Highly selective and sensitive sensors towards specific gas or vapor molecules are essential for environmental monitoring, and for health and safety issues.

Properties of Nanostructured Rutile Titanium Dioxide (TiO<sub>2</sub>) Thin Film Deposited with Silver Sulfide (Ag<sub>2</sub>S) Quantum Dots as Photoanode for Solar Photovoltaic

Titanium dioxide (TiO2) nanoparticles thin film has been successfully prepared by a simple hydrothermal process using Hydrochloric Acid (HCl) as chelating agent and Titanium (IV) Chloride (TiCl4) as precursor. In this study, the nanostructured TiO2 thin films were prepared at different hydrothermal reaction times of 2 hours, 5 hours, and 10 hours, and then Ag2S Quantum Dots (QDs) were deposited on the surface of TiO2 nanoparticles using 6 cycles of Successive Ionic Layer Adsorption and Reaction Deposition (SILAR) method. The surface morphology, crystalline structure and optical characterizations of the films were carried out using Field Emission Scanning Electron Microscopy (FESEM), Atomic Force Microscope (AFM), X-ray Diffraction (XRD) and Ultra-Violet-Visible Near Infrared Spectrophotometer (UV-Vis). For electrical properties, four-point probe investigated the sheet resistance, resistivity, and conductivity of these thin films. TiO2 nanorods were formed with diameter ranged from 33.78 nm to 42.58 nm and the length of TiO2 layer increased as the reaction time increased, from 2.84 μm to 3.93 μm (without Ag2S QDs) and 2.88 μm to 4.85 μm (with Ag2S QDs). When the reaction time reaches 10 hours, nanoflowers can be seen on the surface of film. The XRD results showed that with longer reaction time, the value of full-width at half maximum (FWHM) of the TiO2/ Ag2S QDs thin films decreased from 0.335° to 0.263 while the crystallite size increased from 22.73 nm to 35.39 nm. UV-Vis analysis indicated that the optical band gap of these thin films decreased from 2.68 eV to 2.00 eV (direct) and 2.94 eV to 2.40 eV (indirect) with increased in reaction time. The electrical properties of the films showed that the resistivity varied between 7 x 107 Ω.cm and 5.07 x 107 Ω.cm when the reaction time changed from 2 hours to 10 hours. The conductivity of the TiO2/ Ag2S QDs thin films increased with the increase in hydrothermal reaction time and further increased with the incorporation of Ag2S QDs. Besides, the TiO2 films synthesized hydrothermally for 10 hours showed higher surface roughness as compared to other thin films. The obtained results showed that the TiO2 / Ag2S QDs thin films are applicable as a photoanode for Quantum Dots Sensitized Solar Cell (QDSSCs) applications.

Raman study of ion beam irradiation damage on nanostructured TiO2 thin film

90 MeV Xe and 25.78 MeV Cu ion irradiation effect on nanostructured anatase TiO2 thin film, prepared by sol-gel method, was investigated by Raman spectroscopy. The nonirradiated films show five Raman modes corresponding to the anatase phase. Raman spectra of irradiated films reveal crystalline-amorphous phase transition, fact evidenced by a progressive vanishing of Raman peaks correlated by emergence of a novel broad band at higher fluence, attributed to the amorphous structure. The broadening and blue shift of Raman peaks after irradiation indicate the generation of non-stoichiometric oxygen deficiency caused eventually by a preferential sputtering upon irradiation. A compressive stress was thus developed in the lattice which leads to the shortening of Ti–O bonds and the reduction of the crystallinity. The strain calculations reveal a correlation between the amorphization process and lattice strain enhancement. At higher fluence, the relaxation of the compressive stress may occur and results in volume expansion and hillocks formation. The strain and disorder calculations indicate that Xe irradiated films are completely amorphous, whereas, the anatase phase may still be present in Cu irradiated films. This behavior is explained by the difference in the electronic stopping power, which is manifested also in the disorder damage cross section. This latter is similar to that obtained by strain calculations and previously by XRD analysis.

Thermal annealing induced strong photoluminescence enhancement in Ag-TiO2 plasmonic nanocomposite thin films

Thin films of Ag-TiO2 plasmonic nanocomposites were fabricated on silica glass substrates by a combined approach using thermal evaporation and RF magnetron sputtering. The optical and plasmonic response of Ag-TiO2 nanocomposites were tuned with the help of thermal annealing by varying the annealing temperature from 400 °C to 600 °C. The optical absorption spectra revealed the transformation of Ag nanolayer into Ag nanoparticles upon annealing. The band gap of Ag-TiO2 nanocomposite thin films varied from 3.09 eV to 2.53 eV due to annealing. AFM studies revealed growth of nanostructures in the Ag-TiO2 nanocomposites with increase in annealing temperature. The average nanoparticle size varied from 27 nm to 230 nm upon annealing. XRD results confirmed the appearance of Ag nanoparticles along with nanostructured anatase TiO2. The photoluminescence spectra of Ag-TiO2 nanocomposites revealed significant enhancement in intensity of UV and defect emissions upon annealing at 600 °C. The observed enhancement originated from the changes in the plasmonic properties of Ag nanostructures in the nanocomposite upon annealing. The observed significant enhancement in the UV emission arises due to the resonant coupling of surface plasmons of Ag nanoparticles with the band edge emission from TiO2 which significantly improved the number of electrons in the conduction band of TiO2. The PL enhancement in the visible region is ascribed to increased creation of shallow traps in TiO2 due to the presence of Ag nanoparticles. This work provides a simple route to strong enhancement in PL intensity of nanostructured TiO2 thin film which is very promising for applications in nanophotonics.

Analytical studies of electrohydrodynamically TiO2 nanostructure

In this paper, we report an alternate technique for the deposition of nanostructured TiO2 thin films using the electrohydrodynamic atomization (EHDA) technique us- ing polyvinylpyrrolidone (PVP) as a stabilizer. The required parameters for achieving uniform TiO2 films using EHDA are also discussed in detail. X-ray diffraction results con- firm that the TiO2 films were oriented in the anatase phase. Scanning electron microscope studies revealed the uniform deposition of the TiO2. The purity of the films is charac- terized by using Fourier transform infrared (FTIR) spec- troscopy and X-ray photoelectron spectroscopy (XPS), con- firming the presence of Ti–O bonding in the films without any organic residue. The optical properties of the TiO2 films were measured by UV-visible spectroscopy, which shows that the transparency of the films is nearly 85% in the visi- ble region. The current–voltage (I –V ) curve of the TiO2 thin films shows a nearly linear behavior with 45 mQ cm of elec- trical resistivity. These results suggest that TiO2 thin films deposited via the EHDA method possess promising applications in optoelectronic devices.

Enhanced photocatalytic performance of nanostructured TiO2 thin films through combined effects of polymer conjugation and Mo-doping

Mo-doped TiO2 [≤ 0.20 wt% Mo; ≤ 0.10 mol% (metal basis)] with conjugated polyvinyl alcohol (TiO2/C-PVA) composite thin films was prepared by sol–gel dip coating on polished fused SiO2 substrates, followed by annealing at 180 °C for 4 h. These conditions were sufficient for solid solubility, despite the unusually low annealing temperature. The annealed thin films consisted of homogeneously distributed individual and slightly agglomerated anatase grains in a continuous C-PVA matrix characterized by the carbon double bond formed upon conjugation. The films exhibited drying shrinkage cracks, which increased consistently in extent with increasing Mo-doping concentration, effectively increasing the number of exposed TiO2 particles. Mo addition enhanced anatase nucleation, recrystallization, and growth at lower doping concentrations (up to ≤ 0.10 wt%), thereby increasing crystallinity. However, increasing doping levels (> 0.10 wt%) appeared to exceed the solubility limit, resulting in supersaturation and significant lattice destabilization. Mo-doping also caused the Ti2p XPS peaks to shift to lower binding energies and the Mo3d peaks to shift to higher binding energies. These data are consistent with thermodynamically unstable Ti4+ → Ti3+ conversion and thermodynamically stable Mo5+ → Mo6+ conversion, which are interpreted in terms of intervalence charge transfer (IVCT), in which charge compensation is achieved through majority Ti4+ → Ti3+ reduction plus Mo5+ → Mo6+ oxidation. Ti3+ concentration also reflects a direct correlation with the Mo-doping concentration and resultant IVCT within the Mo solubility limit and a reverse effect upon supersaturation. There is a correlation with the Eg but this can be attributed to recrystallization rather than a semiconducting effect. No effect of midgap state formation from enhancement of the $$ {\text{V}}_{\text{O}}^{ \cdot \cdot } $$ concentration is expected because IVCT is a redox effect only and dissolution of Mo5+ or Mo6+ would generate Ti vacancies. The methylene blue dye degradation data exhibited the same trend but at a significant level (90.6% degradation), thus indicating that the mechanism dominating the photocatalytic performance is the recrystallization of the anatase and/or the modification of the semiconducting properties induced by Mo-doping, as indicated by the trends in band gap.

Nano structured TiO2 thin films in the efficient removal of β-estradiol from aqueous solution: physico-chemical studies

Nano structured TiO2 thin films in the efficient removal of β-estradiol from aqueous solution: physico-chemical studies

Nanostructured TiO2 thin films by chemical bath deposition method for high photoelectrochemical performance

TiO2 thin films were deposited by simple chemical bath deposition method onto conducting and non-conducting glass substrates. The resulting films were annealed at 300°, 400°, and 500 °C for 3 h. In XRD studies, crystallite size and microstrain from x-ray line broadening profile were estimated by Scherrer’s and Williamson-Hall plot method. Also, structural parameters such as unit cell volume, lattice constants, dislocation density, and stacking fault probability have been calculated. Optical absorption spectra illustrate that the band gap energy has been decreased from 3.45 to 3.19 eV with increasing annealed temperatures. Furthermore, the photoluminescence (PL) spectra exhibited two luminescence centers, one is for near-band-edge emission (NBE) and another is for deep level emission (DLE). From FT-IR spectrum of 400 °C annealed film, it was found that strong band around at 609 cm−1 is associated with the characteristic vibrational mode of anatase TiO2. The morphology and elemental composition of the 400 °C annealed film were investigated by field emission scanning electron microscopy (FESEM) and energy dispersive x-ray (EDS) analysis respectively. Present work deals with a significant photoelectrochemical cell performance of TiO2 thin films annealed at 400 °C and explored the cell parameters like conversion efficiency (η) and fill factor (FF). Finally, it was found that the deposited TiO2 films showed the outstanding PEC performance with supreme photoconversion efficiency 1.94%.

Electrodeposition of nanostructured TiO2 thin film as an efficient bifunctional layer for perovskite solar cells

In this current work, a bifunctional TiO2 thin film with reduced pin-hole effect and enhanced light trapping capability was successfully fabricated by using a facile galvanostatic anodic deposition route in the presence of Brij-58 soft template (ST). The surface morphology of electrodeposited TiO2 thin film using ST confirmed the formation of nano-sized TiO2 particles with improved porous nature than that of TiO2 thin film electrodeposited in the absence of ST. Compared with the conventional scaffold porous layer (PL) fabricated from commercial mesoporous TiO2 composed of ∼30 nm nanoparticles, the electrodeposited TiO2 film using ST demonstrated the reduced pinhole effect and improved light trapping feature. Owing to the bifunctional behavior of electrodeposited TiO2 using ST, the cell efficiency of the perovskite solar cell was achieved up to 17.06% which was ca.10% higher than those with commercial TiO2 nanoparticles.

Investigation of nanostructured TiO2 thin film coatings for DSSCs application using natural dye extracted from jabuticaba fruit as photosensitizers

Solar power is a renewable and promising solution to the today’s world energy needs. Recently, researchers in finding an alternative energy resource for the next generation lead to the production of efficient photovoltaic cells. Herein, dye-sensitized solar cells (DSSCs) containing semiconducting nanostructured TiO2 thin film photoanodes were fabricated by spin-coating technique, using a self-constructed spin coater, which is a simple and cost-effective method. The composition and superficial characteristics of the films were studied by scanning electron microscopy (SEM), atomic force microscopy (AFM), and Fourier transform infrared spectroscopy (FTIR). Microscopic analysis revealed the electrode surface morphology, and microstructure were influenced by spin-coating technique compared to doctor blade method. The natural dyes of anthocyanin were extracted from jabuticaba (Plinia cauliflora) fruit using a simple extraction technique, used as photosensitizers in DSSCs and their characteristics were studied. The extracts showed the UV–Vis absorptions in the 450–600 nm range with broad maxima at ~ 545 nm. FTIR showed the presence of anthocyanin in the dye molecules of jabuticaba fruit, which can be related to a better photon to electron conversion. The photoelectrochemical performance and the efficiency of assembled DSSCs using jabuticaba fruit dye extract were evaluated, and efficiency enhancement was obtained by spin-coated TiO2 electrodes. The efficiency and fill factor of the DSSC using jabuticaba fruit dye were 0.13% and 0.29%, respectively. The results successfully showed that the DSSC, using jabuticaba fruit extract as a dye photosensitizer, is valuable for the preparation of eco-friendly, less-expensive, renewable, and clean sources of energy.

Preparation of transparent nanostructured N-doped TiO2 thin films by combination of sonochemical and CVD methods with visible light photocatalytic activity

Pollution of water resources with pesticide compounds has raised serious environmental problems, and for photocatalytic degradation of these pollutants, thin film photocatalysts are preferred to colloidal ones due to the separation problem of colloidal nanoparticles. In this work, nanostructured TiO2 and N-doped TiO2 thin films with high transparency were deposited on glass and quartz substrates through sonochemical–chemical vapor deposition (CVD) method. The films prepared on glass and quartz substrates had nanocubic and nanospherical morphology, respectively. The presence of N atoms in the structure of TiO2 resulted in a decrease in the band gap energy of TiO2 and also in the reduction of photogenerated electron–hole recombination rate. Furthermore, the presence of N atoms induced the formation of Ti3+ species which can act as hole trapping centers. The prepared thin films were also used for the visible light photocatalytic degradation of paraoxon pesticide. According to these results among the prepared thin films, the N-doped TiO2 thin films have higher photocatalytic activity than pure TiO2 thin films. Moreover, in comparison with the thin films deposited on quartz substrate, the films on glass substrate have higher photocatalytic performance, which can be related to the special nanocubic morphology of these samples.

Oxygen detection using nanostructured TiO2 thin films obtained by the molecular layering method

Using the molecular layering method (ML), nanostructured TiO2 films have been synthesized that are promising for detecting oxygen over a wide range of concentrations at low operating temperatures of 150–300 °C. It has been shown that an anatase thin film is formed; the particle size is 34.9 ± 3.1 nm. It has been established that it enables the highly responsive detection of oxygen (RO2/RAr up to 26.6 at a temperature of 200 °C and O2 content of 10%). The influence of operating temperature on the response values, and response and recovery time, have been studied. It has been shown that response magnitude slightly depends on humidity, but at 100% humidity response time and signal recovery time increase significantly. A sufficiently high degree of selectivity has been found when detecting oxygen, in comparison with other analyte gases (CO, H2, CH4 and CO2).

Single Crystalline-like and Nanostructured TiO2 Photoanodes for Dye Sensitized Solar Cells Synthesized by Reactive Magnetron Sputtering at Glancing Angle

The control of the surface area enhancement and the ordering of the mesoporous photoanode is one of the key parameters to overcome the current limits of performance of dye sensitized solar cells (DSSCs). These parameters are expected to improve both the concentration of adsorbed dye molecules on the photoanode and the charge collection. In this paper, reactive magnetron sputtering at glancing angle is employed to synthesize nanostructured TiO2 thin films. A post-annealing treatment under an ambient atmosphere at 773 K allows recrystallization of the films to form individual single crystal-like anatase nanocolumns, as shown on a reference structure constituted by well-separated slanted nanocolumns. Even if the best cells provide an open circuit voltage of 0.8 V, a fill factor of 77%, and a short circuit current density of 4.6 mA/cm2 (JSC) and permit to reach an overall efficiency up to 2.6%, it does not yet reach the performances of the reference TiO2 nanoparticle (NP)-based cell. This is explained by a po...

Surface modified nanostructured-TiO2 thin films for removal of Congo red

We synthesized nanostructured TiO2 thin films by the modified sol-gel template method using the polyethylene glycol as filler media. The TiO2 surface modification for both the thin films, i.e., template and non-template, was done with the ascorbic acid. All the four thin film samples, S1 (TiO2 (non-template), TiO2 (template), S3 (S1 modified with ascorbic acid) and S4 (S2 modified with ascorbic acid), were characterized by various analytical methods. Phase evaluation was monitored by the X-Ray diffraction analysis. Moreover, the thin films particle sizes were obtained to be 22.32, 21.20, 14.52 and 16.77 nm, respectively for the samples S1, S2, S3 and S4. The changes in particle size and morphology due to the PEG and ascorbic acid were determined by scanning electron microscopy (SEM). Similarly, thermal gravimetric (TG) and differential scanning calorimetry (DSC) were performed to determine the decomposition behavior of organic compound present in the solid samples. The functional groups were determined by infrared (IR) analysis. The photocatalytic efficiency, as a reference of Congo red, was conducted using all the four samples of TiO2 thin films. Complete photocatalytic degradation of Congo red was achieved by these samples within 130, 80, 40 and 30 mins of UV illumination.