双层结构CeO2光阳极在染料敏化太阳能电池中的应用

利用水热法合成核壳结构Au@SiO₂@CeO₂纳米微球,制备了一系列双层结构复合光阳极并应用于染料敏化太阳能电池(DSSC)。研究表明：当CeO₂纳米微球和核壳结构Au@SiO₂@CeO₂纳米微球应用于DSSC光阳极散射层时,电池的光电转化效率有了显著提高。相对于纯TiO₂(P25)光阳极,P25/CeO₂纳米球光阳极电池的DSSC光电性能提高了15.3%,P25/Au@SiO₂@CeO₂纳米球光阳极电池的光电性能提高了27.9%。DSSC光电性能的提高主要归因于2个方面：一方面,Au纳米粒子的表面等离子体共振效应有效提高了光阳极薄膜的光散射效应。另一方面,CeO₂具有较高的染料负载能力,核壳球形结构具有较高的比表面积,增强了光的散射效应,提高了电子传输能力。     

Titania nanocomposite films derived by modified sol-gel process for photovoltaic application

Titania nanocomposite films were fabricated by spin-coating from sol-gel derived pastes of TiO₂ powder in titanium isopropoxide sol. The thin films were characterized for structural, optical and hydrophilic properties and evaluated as electrodes in a photoelectrochemical cell. Addition of TiO₂ powder increased film thickness, reduced transmittance, water contact angle and electrochemical impedance, and promoted photocurrent generation. Increasing Triton X-100 surfactant loading in the composite slurry influenced film texture and transmittance, and the resultant films exhibited a lower photocurrent yield but were more hydrophilic to favor charge transfer at the electrode/electrolyte interface. The aggregation of TiO₂ particles of different sizes in the composite film facilitates light-scattering and electron transport to enhance quantum efficiency. The addition of Triton X-100 surfactant influences the distribution of scattering centers to increase transparency.     

Preparation and photoelectrochemical performance of PbSe/BaTiO3/TiO2 composite film

By dipping-lifting in sol–gel solution and reducing process, the TiO₂ composite film on the glass plate was first prepared. Then, the PbSe/BaTiO₃/TiO₂ composite film was fabricated by interface reaction with BaTiO₃ and PbSe on the surface of TiO₂ composite film. The characterization results show that the uniform porous TiO₂ film is made up of the anatase crystal, and the PbSe/BaTiO₃/TiO₂ composite film is constructed by doping or depositing BaTiO₃ and PbSe nanoparticles on the surface of TiO₂ film. The photoelectrochemical measurement results indicate that the PbSe/BaTiO₃/TiO₂ composite film has an interesting photoelectrochemical conversion property.     

双层结构CeO2光阳极在染料敏化太阳能电池中的应用

利用水热法合成核壳结构Au@SiO₂@CeO₂纳米微球,制备了一系列双层结构复合光阳极并应用于染料敏化太阳能电池(DSSC)。研究表明：当CeO₂纳米微球和核壳结构Au@SiO₂@CeO₂纳米微球应用于DSSC光阳极散射层时,电池的光电转化效率有了显著提高。相对于纯 TiO₂ (P25)光阳极,P25/CeO₂纳米球光阳极电池的 DSSC 光电性能提高了 15.3%,P25/Au@SiO₂@CeO₂纳米球光阳极电池的光电性能提高了27.9%。DSSC光电性能的提高主要归因于2个方面：一方面,Au纳米粒子的表面等离子体共振效应有效提高了光阳极薄膜的光散射效应。另一方面,CeO₂具有较高的染料负载能力,核壳球形结构具有较高的比表面积,增强了光的散射效应,提高了电子传输能力。     

High photocatalytic degradation activity of polyethylene containing polyacrylamide grafted TiO2

A novel photocatalytic polyacrylamide grafted TiO₂ (PAM-g-TiO₂) nanocomposite was prepared and embedded into a low density polyethylene (LDPE) plastic. Photocatalytic degradation of the LDPE/PAM-g-TiO₂ composite film was carried out under ambient conditions under ultraviolet light irradiation. The properties of composite film were compared with those of the pure LDPE film by measuring the changes in weight loss, carbonyl index, molecular weight, tensile strength and elongation at break. PAM-g-TiO₂ embedded LDPE showed highly enhanced photocatalytic degradation. Irradiating the LDPE/PAM-g-TiO₂ composite film for 520 h under UV light reduced its weight by 39.85% and average molecular weight (M_w) by 94.60%, while that of pure LDPE film was only 1.03% and 69.59%, respectively. The addition of PAM-g-TiO₂ brought about the good dispersion of TiO₂ in LDPE matrix and improved the hydrophilicity of composite film, which were able to facilitate the degradation of LDPE. The photocatalytic degradation mechanism of the films is briefly discussed.     

Ag负载KTa1-xNbxO3-BaTiO3颗粒掺杂P(VDF-TrFE-CTFE)复合材料的制备及介电性能

通过光照还原法制备了银颗粒负载的铌钽酸钾-钛酸钡复合粉体（Ag/KTN-BT）,并将其与聚偏氟乙烯-三氟乙烯-三氟氯乙烯（P（VDF-TrFE-CTFE））聚合物复合,获得Ag/KTN-BT聚合物基复合材料。研究发现,Ag/KTN-BT填料颗粒在聚合物基体中分散均匀,复合材料结构致密,无明显气孔和裂纹,且具有较好的柔韧性。银纳米颗粒的负载,一方面在复合材料中引入了额外的界面,导致界面极化作用增强,明显提高复合材料的介电常数;另一方面银纳米颗粒的量子尺寸效应和库伦阻塞效应使得复合材料保持较低的介电损耗。当填充体积分数为20%的Ag/KTN-BT颗粒时,聚合物基复合材料的介电常数大幅提升,从聚合物的37提升到125（100 Hz）,介电损耗仅为0.12。与KTN-BT基复合材料对比,Ag/KTN-BT基复合材料也显示出较好的介电性能。     

Synthesis and characterization of (hydroxypropyl)cellulose/TiO2 nanocomposite films

A new method of synthesis of TiO₂ nanoparticles as well as preparation of the organic–inorganic hybrid nanocomposite films of (hydroxypropyl)cellulose (HPC)/TiO₂ is presented. At the first stage, the oxotitanium hydrogel phase was obtained by the mineralization of (tetra‐isopropyl)orthotitanate (TIPT) modified by the methacrylic acid (MAA) in 15 wt% solution of H₂O₂ at room temperature and subsequent annealing at the temperature of 85°C. The crystallization of the nanoparticles of TiO₂ was conducted at the oxotitanium hydrogel phase at temperatures around 120°C in the closed vessel. Nanocomposite hybrid films were prepared by the casting method from a solution of HPC and TiO₂ nanoparticles in the water. The films of nanocomposite with 10 µm thickness are transparent to visible light and have a lower glass transition temperature compared with HPC in the bulk. This shift of the glass transition is interpreted in terms of packing density of HPC in the interface of HPC nanocomposite with TiO₂. The X‐ray diffraction pattern of the nanocomposite film suggests a lower amount of mesomorphic phase of HPC in the composite compared with HPC in the bulk. Copyright © 2007 John Wiley & Sons, Ltd.     

Development of a Core–Shell Heterojunction TiO2/SrTiO3 Electrolyte with Improved Ionic Conductivity

Lately, semiconductor-membrane fuel cells (SMFCs) have attained significant interest and great attention due to the deliverance of high performance at low operational temperatures, <550 °C. This work has synthesized the nanocomposite core-shell heterostructure (TiO₂−SrTiO₃) electrolyte powder by employing the simple hydrothermal method for the SMFC. The SrTiO₃ was grown in situ on the surface of TiO₂ to form a core-shell structure. A heterojunction mechanism based on the energy band structure is proposed to explain the ion transport pathway and promoted protonic conductivity. The core-shell heterostructure (TiO₂−SrTiO₃) was utilized as an electrolyte to reach the peak power density of 951 mW cm⁻² with an open-circuit voltage of 1.075 V at 550 °C. The formation of core-shell heterostructure among TiO₂ and SrTiO₃ causes redistribution of charges and establishes a depletion region at the interface, which confined the protons′ transport on the surface layer with accelerated ion transport and lower activation energy. The current work reveals novel insights to understand enhanced proton transport and unique methodology to develop low-temperature ceramic fuel cells with high performance.     

Electrochemical preparation of PMeT/TiO<Subscript>2</Subscript> nanocomposite electrochromic electrodes with enhanced long-term stability

In this work, 3-methylthiophene (MeT) was electrochemically incorporated with nano- and mesoporous TiO₂ films to form poly(3-methylthiophene) (PMeT)/TiO₂ nanocomposite electrochromic electrodes. TiO₂ films, which were previously coated on the ITO glass sheets through a well-established technique, were introduced to enhance the adhesion of the polymers to the substrates and thus increase the long-term stability of the devices. With this effort, the nanocomposite electrodes were found to retain up to 60% of their optical response after 3,500 deep and double potential steps and retain up to 50% of their electroactivity after 10⁴ same steps, exhibiting enhanced long-term stability. Switching time and the maximum optical contrast (ΔT%) of the nanocomposite electrodes were found to be 0.6 s and 45%, respectively. Moreover, our work showed that electrochemically incorporating conductive polymers (CPs) with TiO₂ mesoporous films was an effective method to form high-quality CP/TiO₂ nanocomposite electrodes, which can be used widely in battery cathodes, photovoltaic cells, photocatalytic reaction, and photoelectrochromic cells and were supposed to enhance their performances.     

TiO2纳米棒和CdSe纳米棒复合膜与聚3-甲基噻吩杂化太阳能电池研究

采用水热法制备了TiO₂和CdSe两种纳米棒材料, 将两种纳米材料制备成TiO₂/CdSe复合纳米棒膜电极, 并在复合膜上电化学聚合生成聚3-甲基噻吩poly(3-methylthiophene) (PMeT), 研究了其光电化学性能. 实验表明, 当TiO₂与CdSe的物质的量复合比为2∶1, PMeT的聚合时间为40 s, 在电极电势为－0.2 V下ITO/TiO₂/CdSe/PMeT电极光电转换效率(IPCE)达到56%, 对比ITO/TiO₂/CdSe复合膜电极在长波方向的光电转换效率明显提高, 光吸收截止波长发生了明显的红移. 同时以ITO/TiO₂/CdSe/PMeT组装了简易的杂化太阳电池, 初步研究了光电池性能, 光电池总效率为0.08%, V_oc＝0.4 V, j_sc＝0.61 mA/cm², ff＝0.33.     

Highly Selective and Sensitive Detection of Dopamine in the Presence of Excessive Ascorbic Acid Using Electrodes Modified with C60‐Functionalized Multiwalled Carbon Nanotube Films

Electrochemical detection of dopamine (DA) in the presence of a large excess of ascorbic acid (AA) was investigated with a novel all‐carbon nanocomposite film of C₆₀‐MWCNTs (C₆₀‐functionalized multi‐walled carbon nanotubes) using a bare MWCNTs film as control. Although both films can selectively detect DA from AA by separating their oxidation potentials, the C₆₀‐MWCNTs film shows special selectivity and good sensitivity for detecting DA. On one hand, the C₆₀‐MWCNTs composite film shows a higher activity for DA oxidation with enhanced peak current. On the other hand, the C₆₀‐MWCNTs composite film effectively suppresses the oxidation of AA. Remarkably, it is found that the oxidation current of DA is over 2 times higher than that of AA even when the concentration of AA is about 3 to 4 orders of magnitude higher than that of DA. This offers a tremendous advantage for the simple and clean detection of DA free of the interfering AA signal in a real assay. Cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectrometry are used to characterize the C₆₀‐MWCNTs composite film. These novel properties are interpreted to arise from the facile electron transfer between C₆₀ and MWCNTs in the C₆₀‐MWCNTs nanocomposite film.     

Preparation and photoelectrochemical performance of TiO<Subscript>2</Subscript>/Ag<Subscript>2</Subscript>Se interface composite film

Coupling TiO₂ with a narrow band gap semiconductor acting as the photosensitizer has attracted much attention in solar energy exploitation. In this work, the porous TiO₂ film was first formed on the conducting glass plate (CGP) substrate by the decomposition of polyethylene glycol (PEG) mixing in titanium hydroxide sol at 450°C. Then, the TiO₂/Ag²Se interface composite film was fabricated by interface reaction of AgNO₃ with NaSeSO₃ on the activated surface of porous TiO₂ film. The results of SEM and XRD analyses indicated that the porous TiO₂ layer was made up of the anatase crystal, and the Ag₂Se layer was made up of congregative small particles that have low-temperature α-phase structure. Due to its efficient charge separation for the photo-induced electron-hole pairs, the TiO₂/Ag₂Se interface composite film as-prepared has good photovoltaic property and high photocurrent response for visible light, which have been confirmed by the photoelectrochemical measurements.     

Non-cytotoxic and bioactive nanocomposite film of natural Arabic gum incorporating TiO2 nanoparticles for bone tissue regeneration

Biomaterials with exceptional biocompatibility and bioactivity are now pushing the boundaries of bone tissue engineering. In this study, natural Arabic gum biopolymer incorporating titanium dioxide nanoparticles (NAG + TiO₂NP) nanocomposite film was fabricated. The FTIR and XRD analysis show the presence of functional groups assigned to NAG biopolymers and highly crystalline anatase TiO₂NP. Well dispersed TiO₂NP can be seen from SEM micrograph suggesting good interaction between TiO₂NP filler and NAG biopolymer matrix to enhance the mechanical characteristics of nanocomposite film. The NAG + TiO₂NP nanocomposite film exhibited strong bioactivity to form bone-like apatite and promoted the proliferation of MG-63 cells attributed to their excellent biocompatibility and non-toxicity. The NAG + TiO₂NP nanocomposite film also displays high antibacterial activity with (36.33 ± 1.53) mm and (27.00 ± 2.00) mm inhibition zone were recorded against Staphylococcus aureus and Escherichia coli. The findings indicate that the NAG + TiO₂NP nanocomposite film, with its improved mechanical properties, high swelling capacity, biodegradability, and non-toxicity, shows promise as a viable option for bone tissue regeneration materials.     

Structure and photochromic properties of molybdenumphosphoric acid/TiO<Subscript>2</Subscript> composite films

TiO₂ sol-gel composite films with dropping molybdenumphosphoric acid (PMoA) have been prepared by sol-gel method. The structure and constitute of composite thin films were studied with Fourier transforms infrared spectroscopy (FT-IR) atomic force microscopy (AFM), and X-ray diffraction (XRD) patterns, respectively. The photochromic behavior and mechanism of composite thin films were investigated with ultraviolet-visible spectra (UV-vis) and electron spin resonance (ESR). FT-IR results showed that the Keggin geometry of PMoA was still preserved inside PMoA/TiO₂ composite thin films, and a charge transfer bridge was built at the interface of PMoA and TiO₂ through the Mo-O-Ti bond. Surface topography of the composite film showed obvious changes before/after adding PMoA, and the surface topography of composite films showed obvious changes before/after irradiating as well. Composite thin film had reversible photochromic properties. Irradiated with UV light, transparent films changed from colorless to blue and they can bleach completely with ambient air in the dark. ESR results showed that TiO₂ were excitated by UV light to produce electrons, which deoxidized PMoA to produce heteropolyblues. The photochromic process of PMoA/TiO₂ system was carried through electron transfer mechanism.     

Particulate sol–gel synthesis and optical and electrical properties of CeO<Subscript>2</Subscript>/TiO<Subscript>2</Subscript> nanocomposite

CeO₂/TiO₂ nanocomposite was synthesized by particulate sol–gel method. The X-ray diffractogram shows the presence of cubic CeO₂ and anatase TiO₂ in the composite. The high resolution scanning electron micrographs reveal the nanoparticulate nature of the prepared composite. The composite absorbs UV light and exhibits near-band gap emission corresponding to TiO₂ and deep level emission due to crystal defects. The Nyquist plot displays two semicircular arcs indicating the material heterogeneity. The physicochemical characteristics of the synthesized nanocomposite are in favour of its application as an ingredient of sunscreen formulations; under UV light the photocatalytic activity of CeO₂/TiO₂ composite, tested through the degradation of rhodamine B, is very much less than that by pristine anatase TiO₂. Reduced adsorption of moisture by the nanocomposite is a possible reason for the observed very low photocatalytic activity.     

Photocatalytic Nanocomposite Films Fabricated by Layer‐by‐Layer Self‐assembly of TiO2 Nanoparticles and Lignosulfonates

Photocatalytic multilayer nanocomposite films composed of anatase TiO₂ nanoparticles and lignosulfonates (LS) were fabricated on quartz slides by the layer‐by‐layer (LBL) self‐assembly technique. X‐ray photoelectron spectroscopy (XPS), UV‐vis spectroscopy and atomic force microscopy (AFM) were used to characterize the TiO₂/LS multilayer nanocomposite films. Moreover, the photocatalytic properties (decomposition of methyl orange and bacteria) of multilayer nanocomposite films were investigated. XPS results indicated that the intensities of titanium and sulfur peaks increased with the LBL deposition process. A linear increase in absorbance at 280 nm was found by UV‐Vis spectroscopy, suggesting that stepwise multilayer growth occurs on the substrate and this deposition process is highly reproducible. AFM images showed that quartz slide was completely covered by TiO₂ nanoparticles when a 10‐bilayer multilayer film was formed. The decomposition efficiency of methyl orange by TiO₂/LS multilayer films under the same UV irradiation time increased linearly with the number of TiO₂ layers, and the results of decomposition of bacteria under UV irradiation showed that TiO₂/LS multilayer nanocomposite films exhibited excellent decomposition activity of bacteria (Escherichia coil).     

Electrospun TiO2 nanofibers coated with polydopamine for enhanced sunlight-driven photocatalytic degradation of cationic dyes

Controlled polydopamine (PDA)-coated TiO₂ composite nanofibers (NFs) were successfully fabricated via a facile electrospinning process and exposing TiO₂ NFs into a slightly alkaline dopamine solution. Chemical composition, structural morphology, and photocatalytic degradation property of as-prepared TiO₂ NFs and PDA-coated TiO₂ composite NFs were characterized by Fourier transfer infrared, X-ray photoelectron spectra, transmission electron microscopy, UV-vis diffuse reflectance spectra, and photocatalytic degradation experiments. The results indicated that the core-shell TiO₂@PDA composite NFs were successfully prepared and the thickness of PDA shell was highly controlled within several nanometers. And obtained TiO₂@PDA composite NFs exhibited improved photocatalytic performance after PDA coating, which is attributed to the photosensitization of PDA shell. Moreover, with increased pH values of initial solution, both absorption capacity in the dark and photocatalytic performance of TiO₂@PDA composite NFs showed significant improvement. Additionally, the obtained composite NFs showed different degrees of enhancement in photocatalytic performance based on different dyes, which is related to the “bait” effect of PDA shell. Comparing with anionic dyes, TiO₂@PDA composite NFs tended to adsorb and degrade more cationic dye molecules. It is anticipated that the fabricated composite NFs with controlled core-shell structure have great potential to be applied for organic pollutants removal, especially cationic dyes.     

Self-assembly of TiO2/polypyrrole nanocomposite ultrathin films and application for an NH3 gas sensor

TiO₂/polypyrrole (PPy) nanocomposite ultrathin films for NH₃ gas detection were fabricated by the in situ self-assembly technique. The films were characterized by UV–Vis absorption, FT–IR spectroscopy, and atomic force microscopy (AFM). The electrical properties of TiO₂/PPy ultrathin film NH₃ gas sensors, such as sensitivity, selectivity, reproducibility, and stability were investigated at room temperature in air as well as in N₂. The results showed that the optimum gas-sensing characteristics of TiO₂/PPy ultrathin film were obtained in the presence of 0.1?wt% colloidal TiO₂ for 20-min deposition. Compared with pure PPy thin-film sensors, the TiO₂/PPy film gas sensor has a shorter response/recovery time. It was also found that both humidity and temperature had an effect on the operation of the TiO₂/PPy film gas sensor at low NH₃ concentrations.     

Bactericidal effect of an energy storage TiO2–WO3 photocatalyst in dark

TiO₂–WO₃ composite photocatalyst films can be charged with reductive energy by irradiation with ultraviolet (UV) light. The photo-charged film exhibited a moderate bactericidal effect on Escherichia coli during 6-h exposure in dark. On the other hand, the pre-discharged film exhibited no significant bactericidal effect. The moderate bactericidal effect may restrain bacteria from increasing during the night, and the survived bacteria may be killed by TiO₂ due to its strong bactericidal effect in the next day. The photo-charged film generated H₂O₂ by reducing oxygen. The bactericidal effect of the photo-charged film was close to that of H₂O₂ of the generated amount. Thus, the bactericidal effect of the photo-charged TiO₂–WO₃ film can be explained chiefly in terms of the generated H₂O₂.