Multifunctional TiO2 Research Articles

A surface-engineered multifunctional TiO2 based nano-layer simultaneously elevates the corrosion resistance, osteoconductivity and antimicrobial property of a magnesium alloy

Magnesium biometals exhibit great potentials for orthopeadic applications owing to their biodegradability, bioactive effects and satisfactory mechanical properties. However, rapid corrosion of Mg implants in vivo combined with large amount of hydrogen gas evolution is harmful to bone healing process which seriously confines their clinical applications. Enlightened by the superior biocompatibility and corrosion resistance of passive titanium oxide layer automatically formed on titanium alloy, we employ the Ti and O dual plasma ion immersion implantation (PIII) technique to construct a multifunctional TiO2 based nano-layer on ZK60 magnesium substrates for enhanced corrosion resistance, osteoconductivity and antimicrobial activity. The constructed nano-layer (TiO2/MgO) can effectively suppress degradation rate of ZK60 substrates in vitro and still maintain 94% implant volume after post-surgery eight weeks. In animal study, a large amount of bony tissue with increased bone mineral density and trabecular thickness is formed around the PIII treated group in post-operation eight weeks. Moreover, the newly formed bone in the PIII treated group is well mineralized and its mechanical property almost restores to the level of that of surrounding mature bone. Surprisingly, a remarkable killing ratio of 99.31% against S. aureus can be found on the PIII treated sample under ultra-violet (UV) irradiation which mainly attributes to the oxidative stress induced by the reactive oxygen species (ROS). We believe that this multifunctional TiO2 based nano-layer not only controls the degradation of magnesium implant, but also regulates its implant-to-bone integration effectively. Statement of significanceRapid corrosion of magnesium implants is the major issue for orthopaedic applications. Inspired by the biocompatibility and corrosion resistance of passive titanium oxide layer automatically formed on titanium alloy, we construct a multifunctional TiO2/MgO nanolayer on magnesium substrates to simultaneously achieve superior corrosion resistance, satisfactory osteoconductivity in rat intramedullary bone defect model and excellent antimicrobial activity against S. aureus under UV irradiation. The current findings suggest that the specific TiO2/MgO nano-layer on magnesium surface can achieve the three objectives aforementioned and we believe this study can demonstrate the potential of biodegradable metals for future clinical applications.

Multi-functional amorphous TiO2 layer on ZIF-67 for enhanced CO2 photoreduction performances under visible light

Multi-functional amorphous TiO2 (a-TiO2) layer is uniformly decorated on ZIF-67 through a simple hydrothermal and low temperature calcination methods, which promotes the conversion efficiency and selectivity in the photoreduction of CO2 under visible light. The optimized ZIF-67@a-TiO2 demonstrates high CO production of 43.8 μmol after 4 h irradiation with high CO selectivity of 67.2%, which are substantially enhanced compared with that of pristine ZIF-67. State and transient optical and electrochemical tests indicate that the multi-functional a-TiO2 layer not only leads to enhanced utilization of incident light by the effective light scattering effect, but also serves as blocking layer to suppress the charge recombination by restraining the backwards photoelectron flow without interrupting the photoelectron transfer from the photosensitizer to ZIF-67. In addition, the a-TiO2 layer introduces abundant mesoporous characteristics in the catalyst, which facilitates the mass diffusion without scarifying the overall CO2 absorption capacity. Meanwhile, it is tentatively believed that the H3O+ is more likely adsorbed on the hydrophilic a-TiO2 with highly polarized surface, which inhibits the H2 generation and results in the pleasant CO selectivity. Furthermore, the a-TiO2 shell effectively suppresses the photo-corrosion of ZIF-67, which finally leads to the superior photocatalytic performances along with the high stability.

TiO2 nanoparticles incorporation in carbon nanofiber as a multi-functional interlayer toward ultralong cycle-life lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries have attracted many attentions due to their high energy density and low-cost. However, the insulation and volume change of sulfur and high solubility of polysulfides lead to the fast decay of capacity and short cycle life. In order to solve these issues, we synthesized a novel multifunctional TiO2@C composite nanofibers (TiO2@C CNs) interlayer by electrospinning technique and subsequent heat treatment. It can significantly improve the specific capacity and long cycling stability of Li-S batteries, attributed to the effective restriction of “shuttle effect” and high reutilization of trapped active materials. Using TiO2@C CNs as a multifunctional interlayer, the BP2000/sulfur cathode with a high sulfur content (70 wt %) shows an initial capacity of 852 mAh g−1 at a high current rate of 4C and cycled over 2000 cycles with a fade rate of only 0.028% per cycle. The combination of metal oxides and carbon materials is facile and feasible way to archive high performance Li-S batteries.

Multifunctional and recyclable TiO2 hybrid sponges for efficient sorption, detection, and photocatalytic decomposition of organic pollutants

Developing techniques for monitoring and removing organic pollutants such as solvents and dyes in environmental media is a very important task nowadays. To get rid of the pollutants, efficient materials that can sorb, detect, and decompose such compounds have been consistently sought after. Herein, we demonstrate a simple and inexpensive method to fabricate eco-friendly multifunctional and recyclable TiO2 hybrid sponges composed of a polydimethylsiloxane (PDMS) network and functional nanoparticles. Water-soluble crystals were used to construct porous templates and TiO2 nanoparticles were additionally integrated into the templates where liquid PDMS was filled. After curing the PDMS, the TiO2 integrated hybrid sponges were finally obtained by dissolving the templates with water. By using the fabricated hybrid sponges, sorbed organic pollutants were qualitatively detected via molecular-specific Raman signals. Furthermore, we showed the recyclability by achieving photocatalytic decomposition of the sorbed pollutants induced by the TiO2 nanoparticles. These results are instructive for further applications and also contribute toward solving problems relating to environmental pollution.

Antioxidant functionalized silica-coated TiO2 nanorods to enhance the thermal and photo stability of polypropylene

Rutile TiO2 is commonly used as UV shielding agent because of the absorption of UV light. In this research, we integrated the function of rutile TiO2 nanoparticles and antioxidants (AO), and prepared a kind of multifunctional TiO2 nanoparticles with the capacity of both UV absorption and antioxidation. Firstly, rutile TiO2 nanorods were prepared and encapsulated by SiO2 to decrease its photocatalytic activity. Then, antioxidant functionalized silica-coated TiO2 nanorods (AO-KH550-SiO2-TiO2) were successfully synthesized by using aminosilane coupling agent (KH550) as a bridge. By melt blending method, AO-KH550-SiO2-TiO2 were incorporated into PP matrix. The results indicated that AO-KH550-SiO2-TiO2 could improve both photo stability and thermal stability of PP. PP/AO-KH550-SiO2-TiO2 film broke after 220 h UV irradiation, and the broken time of PP/TiO2 film was only 80 h. And the oxidation induction time of PP/AO-KH550-SiO2-TiO2 sample was 4.7 min, while PP/TiO2 sample showed no antioxidation effect. In addition, AO-KH550-SiO2-TiO2 exhibited excellent anti-extraction property. This novel design of AO-KH550-SiO2-TiO2 may open up a new avenue for fabricating multifunctional nanoparticles and facilitating their practical application.

TiO2-alginate composite aerogels as novel oil/water separation and wastewater remediation filters

Developing effective and “green” approaches to handle aquatic pollution problems is currently one of the most important research subjects of environmental remediation. In this paper, an environmentally friendly, low cost, self-cleaning, highly stable and multifunctional TiO2 enhanced Sodium alginate composite (SAT) aerogel for oil-water separation is developed via a simple combined ionic cross-linking and freeze drying method. The morphological, structural and surface chemical properties of the as-prepared SAT aerogels is characterized by scanning electric microscopy (SEM), X-ray diffraction (XRD), Flourier transformation infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The characterizations demonstrate that the SAT aerogel is of three-dimensional porous microstructure with uniformly dispersed TiO2 nanoparticles (NPs) on alginate matrix. The hydrophilic alginate matrix combined with this unique morphostructure will ensure the SAT aerogels with underwater oleophobicity and subsequent excellent oil/water separation efficiency (up to 99.7%). Moreover, the firmly attached TiO2 NPs can also endow the aerogel with better UV-aging resistance, photoinduced self-cleaning and environmental remediation performance. The SAT aerogel exhibits better oil/water separation reusability (at least 60 cycles) compared to SA aerogel and excellent photocatalytic performance for methyl orange (MO) degradation (>85% after 6 times repeated use). The “green” facile fabrication process, excellent oil/water separation, photoinduced self-cleaning and reusable performances make the SAT aerogel promising for practical application in aquatic environments. This work may open up new avenues for designing versatile aerogel for wastewater remediation.

Multifunctional TiO2 overlayer for p-Si/n-CdS heterojunction photocathode with improved efficiency and stability

The application of Si-based photocathode for water splitting is largely limited by the low photovoltage and inherent corrosion in aqueous media, where the extraction of photovoltage from Si always requires high temperature doping or complicated deposition techniques. This paper describes a facile solution processed p-Si/n-CdS heterojunction for low cost photovoltage generation from commercially available p-Si substrates, which is further covered by a TiO2 layer. The multifunctional TiO2 layer serves as 1) a passivation layer to fix surface defects of CdS to reduces surface carrier recombination; 2) a hole-blocking layer to reflect photogenerated holes to improve charge separation; 3) a protective layer to avoid the corrosion of CdS and Si substrate. The p-Si/n-CdS/n-TiO2/Pt photocathode exhibits increased open-circuit voltage (from 49 to 425 mV) and stable H2 production for 1 h. The surface passivation effect and low valence band position of TiO2 both contribute to the improved photovoltage. The solar-to-hydrogen conversion efficiency reaches 2.07%, which is the highest among all Si heterogeneous p-n junction photocathodes in neutral electrolytes.

MRI tracing non-invasive TiO2-based nanoparticles activated by ultrasound for multi-mechanism therapy of prostatic cancer∗∗There is no conflict of interest in this study and no funding has been received for it. We received the approval of the Research Ethics Committee before conducting this study.

To reduce the side effects of chemotherapy and achieve effective and safe therapy for prostate cancer, herein a simple but multi-functional TiO2:Gd@DOX/FA system activated by ultrasound was developed for the MRI-guided multi-mechanism therapy of prostate cancer. TiO2 nanoparticles served as a sonosensitizer as well as a nanocarrier with the pH-responsive release of DOX. The doping of Gd was not only able to endow the TiO2 with magnetic resonance imaging (MRI) ability, but also further improve the sonodynamic ability of the TiO2. The characterization of the as-prepared TiO2:Gd@DOX/FA showed sensitive pH-responsive drug release, high reactive oxygen species (ROS) production, T1-MRI contrast performance and excellent biocompatibility. The cytotoxicity assay in vitro showed cell death up to 91.68% after 48 h incubation induced by the TiO2:Gd@DOX + ultrasound group. Meanwhile, in the in vivo synergistic therapy studies, the tumor sizes of all the nanomedicine groups were smaller than for the free DOX (V:V0 = 4.2). More importantly, the body showed nearly no weight loss. This safety was also confirmed by the H&E staining, biodistribution experiment and serum biochemistry results. Altogether, TiO2:Gd@DOX/FA significantly reduced the side effects of DOX, augmented the levels of ROS and achieved effective and safe therapy, indicating its potential for the multi-mechanism therapy of prostate cancer.

Improved tribocorrosion performance of bio-functionalized TiO2 nanotubes under two-cycle sliding actions in artificial saliva.

After insertion into bone, dental implants may be subjected to tribocorrosive conditions resulting in the release of metallic ions and solid wear debris, which can induce to peri-implant inflammatory reactions accompanied by bone loss, and ultimately implant loosening. Despite the promising ability of TiO2 nanotubes (NTs) to improve osseointegration and avoid infection-related failures, the understanding of their degradation under the simultaneous action of wear and corrosion (tribocorrosion) is still very limited. This study aims, for the first time, to study the tribocorrosion behavior of bio-functionalized TiO2 NTs submitted to two-cycle sliding actions, and compare it with conventional TiO2 NTs. TiO2 NTs grown by anodization were doped with bioactive elements, namely calcium (Ca), phosphorous (P), and zinc (Zn), through reverse polarization anodization treatments. Characterization techniques such as scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and scanning transmission electron microscopy (STEM), were used to characterize the films. Tribocorrosion tests were carried out in artificial saliva (AS) by applying two cycles of reciprocating sliding actions. The open circuit potential (OCP) was monitored before, during, and after both cycles of sliding, during which the coefficient of friction (COF) was calculated. The resulting wear scars were analyzed by SEM and EDS, and wear volume measurements were performed by 2D profilometry. Finally, the mechanical features of TiO2 NTs were accessed by nanoindentation. The results show that bio-functionalized TiO2 NTs display an enhanced tribocorrosion performance, ascribed to the growth of a nano-thick oxide film at Ti/TiO2 NTs interface, which significantly increased their adhesion strength to the substrate and consequently their hardness. Furthermore, it was discovered that during tribo-electrochemical solicitations, the formation of a P-rich tribofilm takes place, which grants both electrochemical protection and resistance to mechanical wear. This study provides fundamental and new insights for the development of multifunctional TiO2 NTs with long-term biomechanical stability and improved clinical outcomes.

Photo-reduction of heavy metal ions and photo-disinfection of pathogenic bacteria under simulated solar light using photosensitized TiO2 nanofibers.

We report the photosensitization of electrospun titania nanofibers, with a mean diameter of 195 nm, by low bandgap silver sulfide nanoparticles of 11–23 nm mean size with the aim of treating heavy metal ions and pathogenic bacteria simultaneously under simulated solar light irradiation. The 17 nm Ag2S/TiO2 nanofibers showed 90% photocatalytic reduction of Cr(vi) at pH of 3 with a pseudo-first order rate constant of 0.016 min−1 which is significantly better than the previously reported for Ag–Ag2S/TiO2 composite particles. The antibacterial capability of the Ag2S/TiO2 nanofibers was evaluated via photo-disinfection of the Gram-positive and Gram-negative bacterial strains. The smallest sized 11 nm Ag2S/TiO2 nanofiber showed the best bactericidal efficiency of 100% and 90.6% against Gram-negative E. coli and Gram-positive S. aureus after 1 h of irradiation, respectively, whereas, only 50% E. coli and 41% S. aureus were found to be inactivated in dark. Furthermore, a UV–O3 treatment of the 11 nm Ag2S/TiO2 nanofibers remarkably enhanced the antibacterial activity where 89% E. coli and 81% S. aureus were inactivated in just 10 min of the irradiation. Enhanced photocatalytic activity is attributed to the efficient charge separation and transfer and reduced electron–hole recombination induced by the effective heterojunction formation between TiO2 and the optimally sized Ag2S nanoparticles. The disinfection nature of the Ag2S nanoparticles, role of the generated hydroxyl species under irradiation, and the cell wall damage mechanism is also discussed. This study demonstrates the potential use of these multifunctional composite TiO2 nanofibers for water remediation.

Protecting of Marble Stone Facades of Historic Buildings Using Multifunctional TiO2 Nanocoatings

Stone surfaces and façades of historic buildings, due to their predominately outdoor location, suffer from many deterioration factors, including air pollution, soluble salts, relative humidity (RH)/temperature, and biodeterioration, which are the main causes of decay. In particular, the façades of the buildings deteriorate with direct exposure to these factors; deformation and disfiguration of superficial decoration and formation of black crusts are often observed on the stones. The development and application of self-cleaning and protection treatments on historical and architectural stone surfaces could be a significant improvement in the conservation, protection and maintenance of Cultural Heritage. A titanium dioxide nanoparticle has become a promising photocatalytic material, owing to its ability to catalyze the complete degradation of many organic contaminants and environmental factors. In this study, TiO2 nanoparticles, dispersed in an aqueous colloidal suspension, were applied directly to historic marble stone surfaces, by spray-coating, in order to obtain a nanometric film over the stone surface. The study started with an investigation of some properties of TiO2 nanoparticles, to assess the feasibility of the use of TiO2 on historic stone and architectural surfaces. Scanning electron microscopy (SEM) was, coupled with energy dispersive X-ray (EDX) microanalysis, (SEM-EDX), in order to obtain information on coating homogeneity and surface morphology, before and after artificial aging; the activity of the coated surface was evaluated through UV-light exposure, to evaluate photo-induced effects. The changes of molecular structure occurring in treated samples were spectroscopically studied by attenuated total reflection infrared spectroscopy (ATR-FTIR); activity of the hydrophobic property of the coated surface was evaluated by Sterio microscopy, model Zeiss 2010 from Munich, Germany, equipped with photo camera S23 under 80X magnification. The efficacy of the treatments was evaluated through capillary water absorption, and colorimetric measurements, performed to evaluate the optical appearance. Results showed that TiO2 nanoparticles are good candidates for coating applications on historic stone surfaces, where self-cleaning photo-induced effects are well evident; they enhanced the durability of stone surfaces toward UV aging, improved resistance to relative humidity (RH)/temperature and abrasion affect, reduced accumulation of dirt on stone surfaces when left in open air for 6 months, and did not alter the original features.

The influence of hybrid alumina/titania materials as electron transmission layer in planar high-performance perovskite solar cells

As one of main layers in hybrid organic–inorganic perovskite solar cells (PSCs), electron transport materials (ETM) play an important role in getting high photoelectric conversion efficiency (PCE). Here, we investigate Al2O3/TiO2 hybrid materials as electron transmission layer in planar perovskite solar cells. The hybrid Al2O3/TiO2 material is proved to induce a better crystal quality of CH3NH3PbCl3−x I x perovskite layer as confirmed by X-ray diffractometer (XRD). The new-formed compact rough surface of ETM is responsible for the better excited electron transmission and light absorption, thus resulting in the improvement of short-circuit current (J sc). Meanwhile, the embedded Al2O3 plays a key role in shifting the conduction band edge of ETM, thereby leading to the improvement of photo-voltage. The optimal value is obtained with the test of sequential changing Al2O3/TiO2 concentration ratio. Compared to the device with pure TiO2 as ETM, the devices assembled with Al2O3/TiO2 hybrid ETM showed improvement in J sc (from 13.65 to 18.71 mA/cm2) as well as in V oc (from 0.95 to 1.00 V), which brings about 27.6% enhancement in PCE based on the multifunctional hybrid TiO2/ Al2O3 ETM.

Encasing Si particles within a versatile TiO2−xFx layer as an extremely reversible anode for high energy-density lithium-ion battery

The chemical phenomena occurring at the electrode-electrolyte interfaces profoundly determine the cycle behavior of a lithium ion battery. In this work, we report that silicon-based anodes can attain enhanced levels of capacity retention, rate performance and lifespan when a versatile protective layer of, F-doped anatase (TiO2−xFx), is applied towards taming the interfacial chemistry of the silicon particles. With careful choice of titanium fluoride as a precursor, internal voids can be generated upon in-situ fluoride etching of the native oxide layer and are used to alleviate the mechanical stress caused by volume expansion of silicon during cycling. In the course of F-doping, part of the Ti4+(d0) ions in anatase are reduced to Ti3+(d1), thereby increasing charge carriers in the crystal structure. Hence, the multifunctional F-doped TiO2−x coating, not only minimizes the direct exposure of the Si surface to the electrolyte, but also improves the electronic conductivity via inter-valence electron hopping. The best-performing composite electrode, Si@TiO2−xFx-3, delivered a satisfactory performance in both half-cell and full-cell configurations. Furthermore, we present a study of 1) the Si valence change at the buried interface using synchrotron based hard X-ray photoelectron spectroscopy, and 2) the phase transformation of the electrode monitored in operando using X-ray diffraction. Based on these characterizations, we observe that the Li+ conducting intermediate phase (LixTiO2−xFx) formed inside the surface coating enables deep lithiation and delithiation of the silicon during battery operation, and thus increase the capacity that can be accessed from the electrodes.

Deposition of multifunctional TiO2 and ZnO top-protective coatings for CSP application

Abstract In this work, high quality, transparent multifunctional and smart anatase TiO 2 and wurtzite ZnO top protective coatings used for CSP silver-based first-surface thick glass mirrors are studied. The TiO 2 and ZnO top-coatings are deposited using chemical spray pyrolysis technique which conserves a very good specular reflectance of the mirrors (94% reflectance in the Near Infrared range). The photocatalytic activity of the prepared top-coatings is evaluated using the methylene blue dye (MB) as a model molecule, and the highest activity is observed for ZnO top-coating, with a degradation efficiency of 42%. Moreover, the effect of post-annealing treatment on the photocatalytic degradation of the top-coatings is pointed out, and is explained in terms of crystallinity and surface morphology. The increase of the photocatalytic activity can be achieved by increasing surface roughness, which is a conflicting requirement with optical transparency needed for concentrated solar power (CSP) top-coating application. Furthermore, it is pointed out that TiO 2 and ZnO top protective thin films exhibit a photo-induced switching of their wetting properties only after 30 min of UV exposure, and their usability as multifunctional top-protective layers for CSP application is discussed.

Multifunctional P-Doped TiO2 Films: A New Approach to Self-Cleaning, Transparent Conducting Oxide Materials

Multifunctional P-doped TiO2 thin films were synthesized by atmospheric pressure chemical vapor deposition (APCVD). This is the first example of P-doped TiO2 films with both P5+ and P3– states, with the relative proportion being determined by synthesis conditions. This technique to control the oxidation state of the impurities presents a new approach to achieve films with both self-cleaning and TCO properties. The origin of electrical conductivity in these materials was correlated to the incorporation of P5+ species, as suggested by Hall Effect probe measurements. The photocatalytic performance of the films was investigated using the model organic pollutant, stearic acid, with films containing predominately P3– states found to be vastly inferior photocatalysts compared to undoped TiO2 films. Transient absorption spectroscopy studies also showed that charge carrier concentrations increased by several orders of magnitude in films containing P5+ species only, whereas photogenerated carrier lifetimes—and thus...

The photoelectrochemical exploration of multifunctional TiO2 mesocrystals and its enzyme-assisted biosensing application.

Mesocrystals, as the assemblies of crystallographically oriented nanocrystals, have single-crystal-like atom structures and scattering features but with much higher porosity than single-crystalline materials, making them promising substitutes for conventional single crystals in photoelectrochemical application. As a proof-of-concept, a series of photoelectrochemical tests were investigated to understand the influence of the differences between them on photoelectrochemical activity. Expectedly, comparing with TiO2 single crystals, TiO2 mesocrystals demonstrated higher photoelectrochemical capability, which provides unique new opportunities for materials design in the fields of solar-energy conversion and catalysis. Therefore, an elegant photoelectrochemical biosensing platform was firstly developed by virtue of carbon nanohorns with outstanding electrical conductivity support multifunctional TiO2 mesocrystals to accelerate the transfer of photogenerated electrons, and then horseradish peroxidase was introduced through the immune recognition reaction for enzyme-assisted in situ generating CdS QDs. The multiplex amplification strategy successfully achieved the ultrasensitive detection of α-fetoprotein antigen. Promisingly, the successful application of multiplex amplification strategy affords a rational and practical consideration for the fabrication of new and high-performance photoelectrochemical sensing devices.

Potential application of functional porous TiO2 nanoparticles in light-controlled drug release and targeted drug delivery

Novel multifunctional porous titanium dioxide (TiO2) nanoparticles modified with polyethylenimine (PEI) were developed to explore the feasibility of exploiting the photocatalytic property of titanium dioxide to achieve ultraviolet (UV) light triggered drug release. Additionally, in order to further realize targeting delivery, folic acid, which chemically conjugated to the surface of the functionalized multifunctional porous TiO2 nanoparticles through amide linkage with free amine groups of PEI, was used as a cancer-targeting agent to effectively promote cancer-cell-specific uptake through receptor-mediated endocytosis. And a typical poorly water-soluble anti-cancer drug, paclitaxel, was encapsulated in multifunctional porous TiO2 nanoparticles. The PEI on the surface of multifunctional porous TiO2 nanoparticles could effectively block the channel to prevent premature drug release, thus providing enough circulation time to target cancer cells. Following UV light radiation, PEI molecules on the surface were cut off by the free radicals (OH and O2−) that TiO2 produced, and then the drug loaded in the carrier was released rapidly into the cytoplasm. Importantly, the amount of drug released from multifunctional porous TiO2 nanoparticles can be regulated by the UV-light radiation time to further control the anti-cancer effect. This multifunctional porous TiO2 nanoparticle exhibits a combination of stimuli-triggered drug release and cancer cell targeting. The authors believe that the present study will provide important information for the use of porous TiO2 nanomaterials in light-controlled drug release and targeted therapy.

TiO2(R)/VO2(M)/TiO2(A) multilayer film as smart window: Combination of energy-saving, antifogging and self-cleaning functions

A novel Multifunctional TiO2(R)/VO2(M)/TiO2(A) multilayer film is designed and deposited by medium frequency reactive magnetron sputtering. An exciting fact that the antifogging, self-cleaning and energy-saving effects are integrated into the multilayer film could offer significant potential for wider applications of smart window. Thereinto, the bottom TiO2 layer with rutile phase plays an important role in the formation of monoclinic phase of VO2 layer and serves as an antireflection layer. Then, the VO2 layer with dominant monoclinic phase performs an automatic solar/heat control for saving energy. Finally, the top TiO2 layer containing a mixed phase of anatase and rutile displays the remarkable photocatalytic and photoinduced properties. According to optical tests, the multilayer film shows satisfactory optical properties with an excellent solar regulation efficiency (ΔTsol=10.2%) and an applicable luminous transmittance (Tlum-L=30.1%) in a low-temperature state. In addition, the multilayer film implements a photoinduced super-hydrophilicity (~ 2.1°) through UV-irradiation, resulting in an antifogging effect. A high level of photocatalytic activity is detected on the surface of the multilayer film through degradation of stearic acid and rhodamine B.

Multifunctional TiO2Microflowers with Nanopetals as Scattering Layer for Enhanced Quasi-Solid-State Dye-Sensitized Solar Cell Performance

Say it with flowers: A multifunctional microflower-like TiO2 structure with nanopetals is successfully synthesized and applied as a scattering layer in a quasi-solid-state dye-sensitized solar cell, which exhibits an improved efficiency compared to the commercial scattering layer.

Superhydrophobic TiO2–Polymer Nanocomposite Surface with UV-Induced Reversible Wettability and Self-Cleaning Properties

Multifunctional superhydrophobic nanocomposite surfaces based on photocatalytic materials, such as fluorosilane modified TiO2, have generated significant research interest. However, there are two challenges to forming such multifunctional surfaces with stable superhydrophobic properties: the photocatalytic oxidation of the hydrophobic functional groups, which leads to the permanent loss of superhydrophobicity, as well as the photoinduced reversible hydrolysis of the catalytic particle surface. Herein, we report a simple and inexpensive template lamination method to fabricate multifunctional TiO2-high-density polyethylene (HDPE) nanocomposite surfaces exhibiting superhydrophobicity, UV-induced reversible wettability, and self-cleaning properties. The laminated surface possesses a hierarchical roughness spanning the micro- to nanoscale range. This was achieved by using a wire mesh template to emboss the HDPE surface creating an array of polymeric posts while partially embedding untreated TiO2 nanoparticles selectively into the top surface of these features. The surface exhibits excellent superhydrophobic properties immediately after lamination without any chemical surface modification to the TiO2 nanoparticles. Exposure to UV light causes the surface to become hydrophilic. This change in wettability can be reversed by heating the surface to restore superhydrophobicity. The effect of TiO2 nanoparticle surface coverage and chemical composition on the mechanism and magnitude of wettability changes was studied by EDX and XPS. In addition, the ability of the surface to shed impacting water droplets as well as the ability of such droplets to clean away particulate contaminants was demonstrated.