TiO2 Nanofilms Research Articles

Design of a solar-driven TiO2 nanofilm on Ti foil by self-structure modifications

A novel solar-driven VO–N–TiO2 (A/R) nanofilm was designed. Its optical absorption can cover the ultraviolet, visible and near-infrared region.

Effect of post-synthesis acid activation of TiO2 nanofilms on the photocatalytic efficiency under visible light

Nanosized TiO2 films were deposited by spray pyrolysis and thermally treated at 400oC. Then the films were dipped in 1M aqueous solution of HCl. The activated samples were divided into two parts - one part was dried (A) and another was annealed (AT) in air. The photocatalytic degradation of Reactive Black (RB5) textile dye under visible light was tested. The following instrumental methods: X-ray diffraction (XRD), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) were applied for the phase and surface characterization of obtained samples. According to Raman and XRD analyses all films are anatase. The XRD showed that activated films are better crystallized than non activated TiO2 film. The presence of chlorine at 200.3 eV was registered for acid activated samples by X-Ray photoelectron spectroscopy. The acidic activated films exhibited higher rate of dye photodegradation than that of the reference TiO2 sample. The photocatalytic efficiency decreases in the order A > AT> non activated TiO2 films. The degradation rate constant for acid activated films is two times higher than those of the reference film. The hydroxyl content in TiO2 acidic activated films is greater than that of the non- activated films, which results in significant increase in the photocatalytic activity. In addition, the presence of chlorine may also lead to enhancement in efficiency.

Fabrication of La-doped TiO2 Film Electrode and investigation of its electrocatalytic activity for furfural reduction

Lanthanum trivalent ions (La3+) doped nano-TiO2 film electrode was prepared by the sol–gel method. The prepared electrode was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV). The electrocatalytic properties of the roughened TiO2 film electrode towards the electrocatalytic reduction of furfural to furfural alcohol were evaluated by CV and preparative electrolysis experiments. The results of the optimum molar ratio of La: Ti was 0.005:1. Experimental evidence was presented that the La nano-TiO2 electrode exhibited higher electrocatalytic activity for the reduction of furfural than the undoped nano-TiO2 electrode in N,N-dimethylformamide medium. Bulk electrolysis studies were also carried out for the reduction of furfural and the product was confirmed by NMR.

Series-Interconnected Plastic Dye-Sensitized Solar Cells Prepared by Low- Temperature Binder-Free Titania Paste

The aim of this research is to study dye-sensitized solar cells (DSSC). This was implemented on a flexible polyethylene terephthalate (PET) substrate using a mixture of transparent and scattered mesoporous anatase-titania as the electron transport layer for the photoelectrode. This mixture of anatase titania performed a dual function of light scattering and efficient dye absorption. In this study, a porous nano-TiO2 film was prepared on indium tin oxide (ITO) coated polyethylene terephthalate (PET) by using a binder-free titania paste; on it, a DSSC was fabricated. The paste which contained a mixture of TiO2 nanoparticles, acid chloride, and ethanol was printed on two patterns of 1x6 cm2 active areas followed by sintered at 120 ºC to form TiO2 films. A commercial dye, N719, was adsorbed on the surface of TiO2 films and assembled to two platinized conductive plastic patterns to form a counter electrode and thus a sandwich-type dye cell. Finally, a solution of KI/I2 electrolytes was injected into the cell in which a couple of sandwich-type dye cells with an active area of 6 cm2 for each cell were series interconnected with a z-type interconnection between the photoelectrode of one cell and the counter electrode of another cell. The cell performance was characterized by employing simulated solar light at an intensity of 50 mW/cm2. The results showed interconnected cells generating a short-circuit photocurrent density of 2.34 mA/cm2, an open-circuit voltage of 1.10 volt, and overall 0.172% power conversion efficiency.

Boron and sulfur co-doped TiO2 nanofilm as effective photoanode for high efficiency CdS quantum-dot-sensitized solar cells

A modified polysulfide redox couple, (CH3)4N)2S/((CH3)4N)2Sn, was employed in CdS quantum dots (QDs) sensitized B/S co-doped TiO2 solar cell with NiS as counter electrode, followed by chemical bath deposition (CBD) in an organic solution to prepare the QDs-cell to ensure high wettability and superior penetration ability of the B/S co-doped TiO2 films, with the co-doping of B/S in TiO2, its band-gap was narrowed and significantly extended the light capture range, and an enhanced energy conversion efficiency of up to 3.6% was observed under AM 1.5 G illuminations, with a significantly high Voc of 1.217 V, a high ff of 88.2% and a short-circuit photocurrent (Jsc) of 3.35 mA cm−2.

Microstructure and adhesive properties of TiO2 coating on PU and PVC leathers

Titanium dioxide (TiO2) films were deposited onto polyurethane (PU) and polyvinyl chloride (PVC) leather by magnetron sputtering, respectively. The crystal structure of the prepared film was studied using X-ray diffraction (XRD) and the surface morphology of the TiO2 films was investigated by scanning electron microscopy (SEM) and atomic force microscope (AFM). The SEM and AFM observations revealed that the surface roughness of the substrates was an extremely important influencing factor on the morphology of the TiO2 films. Moreover, a calculation formulation on the weight loss of per peeling force was proposed to determine the bonding strength between the TiO2 films and the substrates. It was found that the adhesive performance of the TiO2 nanofilms coating on PVC leather was better than that on the substrate of the PU leather.

Existence, release, and antibacterial actions of silver nanoparticles on Ag-PIII TiO₂ films with different nanotopographies.

Nanotopographical TiO2 films (including nanorod, nanotip, and nanowire topographies) were successfully fabricated on the metallic Ti surface via hydrothermal treatment and then underwent Ag plasma immersion ion implantation to incorporate Ag with TiO2. The surface morphology, phase component, and chemical composition before and after Ag–PIII were characterized. In view of the potential clinical applications, both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus were used to estimate their antimicrobial effect. The nanostructured TiO2 films on a Ti surface exhibit a better bacteriostatic effect on both microbes compared to the pristine Ti. The nanotopographies of the TiO2 films affect the nucleation, growth, and distribution of Ag nanoparticles in the films during Ag–PIII process. The Ag nanoparticles are completely embedded into the nanorod film while partially exposed out of the nanotip and nanowire films, which account for the significant differences in the release behaviors of Ag ions in vitro. However, no significant difference exists in their antimicrobial activity against both microbes. The antimicrobial actions of the Ag@TiO2 system described here consist of two methods – the contact-killing action and the release-killing action. Nevertheless, based on the observed results, the contact-killing action should be regarded as the main method to destroy microbes for all the Ag plasma-modified TiO2 nanofilms. This study provides insight to optimize the surface design of Ti-based implants to acquire more effective antimicrobial surfaces to meet clinical applications.

Research on UV/TiO2 Photocatalytic Oxidation of Organic Matter in Drinking Water and its Influencing Factors

UV/TiO2 photocatalytic of filtrated water are conducted in S waterworks which take Yangtze River as its source water in Nanjing. Self-made glass supported nano-TiO2 film and photocatalytic reactor are used for the experiment. Results show that TOC removal efficiency can reached 45% -63% within 2h-3h, Organic matter removal efficiency is positively related with the • OH generated in photocatalytic process. The influence factors on TOC removal efficiency follows the sequence: light intensity, dissloved oxygen, reaction time and pH. Changes of UV absorption characteristics in photocatalytic process indicate that the saturation of organic matter increase significantly, this is conductive to control the risk taken by disinfection by-products. Results proved that UV/TiO2photocatalytic is a promising technology for the removal of organic pollutants in drinking water, it can improved the chemical safety of drinking water.

Atom diffusion and bonding behaviour between titania nanofilm and glass substrate

TiO2 nanofilms added with cerium ion were coated on the glass substrate using the sol–gel procedure. The films thickness with different coating times increased from 40 to 200 nm. The films were characterised by SEM, EDS and FT-IR. The results indicated that the surface morphology of TiO2 nanofilms improved with the coating times increasing and Ce4+ addition. Moreover, in the process of heat treatment, atom interdiffusion and chemical bonding occurred between TiO2 nanofilms and substrates.

Research on Antimicrobial Activity and Packaging Performance of Degradable Protein Films

The degradable protein film-forming materials contained 5% whey protein isolate (WPI), 2% sodium caseinate (NaCas) and 50% glycerol,which was the optimal formula obtained by uniform design method of previous work. The antimicrobial activity and packaging performance of WPI-NaCas degradable protein films were discussed by addition of nanoTiO2 at different concentrations (0,0.05,0.10,0.15,0.20g•(200ml)-1) in film-forming solution.The results showed that nanoTiO2 and protein films showed a certain degree of compatibility.Addition of nanoTiO2 could improve tensile strength and elongation at break of the protein films and decrease WVP values of the films,but decrease light transmittance,increase haze of the protein films. The degradable protein films suited for using below150°C.And,nanoTiO2 incorporated into protein films had antimicrobial activity against both E.coli and S.aureus.

Adsorption of sediment phosphorus by porous ceramic filter media coated with nano-titanium dioxide film

The porous ceramic filter media (PCFM) was applied to reduce the release of P in lake sediment and we wondered if the nano-TiO2 coating could enhance the P adsorption by PCFM alone in lake sediments. The nano-TiO2 film coated on PCFM in this study was prepared by sol–gel process, and the adsorption properties of sediment P in all fractions by the nano-TiO2 film coated PCFM were investigated through a series of stirring and static experiments. P release characteristics and various batch sorption conditions, e.g., adsorbent dosage, stirring time, operation temperature and pH were tested, and the kinetics of sediment P adsorption was discussed. The results showed that the sediment released only a small amount of TP within 8h. The removal efficiency of sediment P in all fractions could reach maximum in 8h and 22d under stirring and static experiments, respectively. The residual concentration of Ca-P, Fe/Al-P, IP, OP and TP in the sediment was 85mg/kg, 255mg/kg, 310mg/kg, 95mg/kg and 431mg/kg, respectively, and the corresponding removal rate was 19.04%, 44.81%, 43.04%, 45.09% and 44.10%, respectively, under the optimal conditions: adsorbent dosage 4g, operation temperature 30°C and pH 2. The adsorption kinetic models of the sediment P in all fractions could be described well by power function equations (Qt=k·ta, 0<a<1). The results suggest that the adsorption of sediment P onto the nano-TiO2 film coated PCFM had the great potential to reduce the pollution of internal phosphorus and regulate the transport of sediment P in the aquatic environment.

Energy dependence on formation of TiO2 nanofilms by Ti ion implantation and annealing

TiO2 nanofilms were fabricated by a solid-phase-growth progress. The silica glass slides were implanted with Ti ions to the fluence of 1.84×1017ions/cm2 at accelerate voltages of 20, 50, and 80kV, respectively. The samples were annealed in oxygen atmosphere at 700, 800, 900, and 1000°C for 4h, respectively. The influence of the ion energy and the annealing temperature on the formation and phase transformation of the TiO2 films was studied. It was found that anatase TiO2 nanofilms instead of embedded rutile TiO2 nanoparticles on the substrate surfaces when the energy of implanted Ti atoms was 20kV.

A Combined Negative and Positive Enrichment Assay for Cancer Cells Isolation and Purification.

Cancer cells that detach from solid tumor and circulate in the peripheral blood (CTCs) have been considered as a new "biomarker" for the detection and characterization of cancers. However, isolating and detecting cancer cells from the cancer patient peripheral blood have been technically challenging, owing to the small sub-population of CTCs (a few to hundreds per milliliter). Here we demonstrate a simple and efficient cancer cells isolation and purification method. A biocompatible and surface roughness controllable TiO2 nanofilm was deposited onto a glass slide to achieve enhanced topographic interactions with nanoscale cellular surface components, again, anti-CD45 (a leukocyte common antigen) and anti-EpCAM (epithelial cell adhesion molecule) were then coated onto the surface of the nanofilm for advance depletion of white blood cells (WBCs) and specific isolation of CTCs, respectively. Comparing to the conventional positive enrichment technology, this method exhibited excellent biocompatibility and equally high capture efficiency. Moreover, the maximum number of background cells (WBCs) was removed, and viable and functional cancer cells were isolated with high purity. Utilizing the horizontally packed TiO2 nanofilm improved pure CTC-capture through combining cell-capture-agent and cancer cell-preferred nanoscale topography, which represented a new method capable of obtaining biologically functional CTCs for subsequent molecular analysis.

Fabrication and Characterization of Superhydrophobic Film on Titanium Substrate

TiO2 nano film with different nano structure were prepared on the surfaces of titanium TA1 and titanium alloy TC4 via electrochemical anodization. The surface morphology was observed with SEM, and it is found that TiO2 films prepared on TA1 surface have porous structures, while the TiO2 films synthesized on TC4 surface look like nano rod. The contact angle(CA) test results show that the TiO2 nano film prepared on TA1 is hydrophilicity and the CA is about 19°,the film on the TC4 is super hydrophilicity and its CA is smaller than 2°. After combined with fluorinated silane the self-assembled film synthesized on the surfaces and they are superhy- drophobic and the Contact angle is 150° and 158° respectively. It is concluded that both nano- structures and fluoroalkysilanes with low surface energy have play an important role in the wettability with the contact angle is more than 150°. The surface only have nano roughness without the low energy does not show superhydrophobicity.

A Novel Way to Fabricate Superhydrophilic and Antibacterial TiO2 Nanofilms on Glass by Ion Implantation and Subsequent Annealing

We report a simple and novel method to fabricate high quality titanium dioxide (TiO2) nanofilms on soda lime glass by a solid phase growth process of Ti implantation and subsequent annealling at 500 °C in oxygen atmosphere. The formation of the TiO2 nanofilms is resulted from the slow out-diffusion of implanted Ti ions from the substrates and being oxidized at the surfaces. The formed TiO2 nanofilms show superhydrophilicity and good antibacterial property with good adhesion to substrate and stability, suggesting that the TiO2 nanofilms formed by this method have great potential applications such as antibacterial, anti-fog and self-cleaning transparent glass.

Tribological properties of titania nanofilms coated on glass surface by the sol–gel method

Ce3+-doped and undoped TiO2 nanofilms with one, three, and five layers were prepared on glass surface by the sol–gel method. The thicknesses were about 40, 120 and 200nm. Atomic force microscopy analysis showed that many defects existed on uncoated glass substrate surface such as microcracks and microvoids, resulting in high surface roughness. After coating with the TiO2 nanofilms, the microdefects of the glass surface were filled and covered by film materials. With increased film layers and Ce3+ doping, the structure of the TiO2 nanofilms surface became more uniform and compact, and the surface roughness gradually decreased. Nanoindentation and friction wear tests on the samples surface revealed that the surface hardness and friction coefficient of uncoated glass substrate were about 6.8GPa and 0.37. After coating, the surface hardness of the samples increased and the friction coefficient remarkably decreased. Furthermore, with increased film thickness and Ce3+ doping, the friction coefficient of the sample gradually decreased and its wear-resisting property obviously increased. TiO2 nanofilms coated on the glass substrate surface can be used as protective layers of glass, exerting excellent anti-wear and friction reducing effects.

Electro-Catalytic Reduction Performance of La-Doped Nano-TiO&lt;sub&gt;2&lt;/sub&gt; Electrode

Homogeneous and transparent lanthanum La-doped TiO2 nanocrystalline thin films were deposited on pure titanium substrates by sol gel dip coating method. The surface structures, morphologies and electrocatalytic activities of the prepared nano-TiO2 film electrodes were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Cyclic voltammetry (CV). The results demonstrated that the optimum molar proportion of La was 0.5%. This optimum La-nanoTiO2 electrode (Ti/0.5%La nano-TiO2) showed a higher electrocatalytic activity than the undoped nano-TiO2 electrode (Ti/nano-TiO2)

Fabrication and properties of TiO2 nanofilms on different substrates by a novel and universal method of Ti-ion implantation and subsequent annealing

We report a new, novel and universal method to fabricate high-quality titanium dioxide (TiO2) nanofilms on different substrates by a solid phase growth process of ion implantation and subsequent annealing in oxygen atmosphere. Ti ions were implanted into fused silica, soda lime glass, Z-cut quartz, or (0001) α-sapphire by a metal vapor vacuum arc (MEVVA) ion source implanter to fluences of 0.75, 1.5 and 3 × 1017 ions cm−2 with a nominal accelerating voltage of 20 kV. To understand the influence of the annealing temperature, time, and substrate on the formation and phase transformation of the TiO2 nanofilms, the Ti-ion-implanted substrates were annealed in oxygen atmosphere from 500 to 1000 ° C for 1–6 h. The formation of TiO2 nanofilms resulted from the slow out-diffusion of implanted Ti ions from the substrates which were then oxidized at the surfaces. The thickness and phase of the nanofilms can be tailored by controlling the implantation and annealing parameters. Since the TiO2 nanofilms are formed under high temperature and low growth rate, they show good crystallinity and antibacterial properties, with good film adhesion and stability, suggesting that the TiO2 nanofilms formed by this method have great potential in applications such as antibacterial and self-cleaning transparent glass.

Surface characteristics, corrosion behavior, and antibacterial property of Ag-implanted NiTi alloy

NiTi shape memory alloy was modified by Ag ion implantation with different incident doses to improve its antibacterial property. The atomic force microscopy, auger electron spectroscopy, and X-ray photoelectron spectroscopy show that the surface of NiTi alloy is covered by TiO2 nano-film with embedded pure Ag with a peak concentration of 5.0 at% at the incident dose of 1.5 × 1017 ions·cm−2, and Ni concentration is reduced in the superficial surface layer. The surface roughness reaches the maximum value nearly twice higher than the control sample at the incident dose of 1.5 × 1017 ions·cm−2. The potentiodynamic anodic polarization curves show that the Ag-implanted NiTi samples possess higher self-corrosion potential (E corr) and lower self-corrosion current density (i corr) but lower breakdown potential (E br). Therefore, the corrosion resistance of the Ag–NiTi is comparable to, if not better than, the untreated NiTi. The antibacterial tests reveal that there is a distinct reduction of the germ numbers on the Ag–NiTi, which is due to the direct contact between Ag and germ, and enhanced by the leaching Ag ions.

Synthesis and Characterization of Modified Nano-TiO2 Films for Corrosion Protection of Stainless Steel

A TiO2 film and a B-Fe-Ce-modified TiO2 film were prepared on the surface of 316L stainless steel (316L SS) substrates by a sol-gel and dip-coating method. The corrosion resistance of the films and their protective properties for the stainless steel were investigated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curve measurements. The results showed that the TiO2 film and the B-Fe-Ce-modified TiO2 film were composed of anatase TiO2 nanoparticles with the diameters about 15 nm and 10 nm, respectively. The EIS results suggested that the B-Fe-Ce-TiO2 film could provide more effective corrosion protection for 316L SS in 0.5 M NaCl solution. The potentiodynamic anodic polarization curve of the B-Fe-Ce-TiO2/316L SS electrode in the above solution showed a larger stable passive region and a higher breakdown potential (Eb ) than that of the TiO2/316L SS.