Fabrication of non-enzymatic biosensor based on metallic catalyst-TiO2 hollow sphere nanocomposite for determining biomolecules

A PtRu@TiO2-hollow nanocomposite for the detection of biomolecules was synthesized by chemical reduction. First, poly(styrene-co-vinylphenylboronic acid), PSB, was prepared as a template (approximately 250 nm) by surfactant-free emulsion polymerization. Second, PSB/TiO2 core-shell spheres were prepared by sol-gel reaction. Finally, TiO2 hollow spheres (TiO2-H) were then formed after removing the PSB template by calcination at 450 degrees C under air atmosphere. To prepare the electrocatalyst, PtRu nanoparticles (NPs) were deposited onto the TiO2-H surface by chemical reduction. The prepared PtRu@TiO2-H nanocomposite was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and elemental analysis. A non-enzymatic sensor was fabricated by depositing the as-prepared PtRu@TiO2-H nanocomposite on the surface of a glassy carbon electrode (GCE), which was prepared by a hand casting method with Nafion solution as a binder. The sensor was tested as a biomolecule sensor, especially for the detection of glucose and dopamine. The cyclic voltammograms (CV) obtained during the oxidation studies revealed that the PtRu@TiO2-H nanocomposite showed better catalytic function toward the oxidation of dopamine. The sensing range of the non-enzymatic sensor for glucose was 5.0-100 mM in a phosphate buffer. The results demonstrated the potential usefulness of this bimetallic@TiO2-H bifunctional catalyst for biosensor applications.     

Cluster synthesis of monodisperse rutile-TiO2 nanoparticles and dielectric TiO2-vinylidene fluoride oligomer nanocomposites

The embedding of oxide nanoparticles in polymer matrices produces a greatly enhanced dielectric response by combining the high dielectric strength and low loss of suitable host polymers with the high electric polarizability of nanoparticles. The fabrication of oxide-polymer nanocomposites with well-controlled distributions of nanoparticles is, however, challenging due to the thermodynamic and kinetic barriers between the polymer matrix and nanoparticle fillers. In the present study, monodisperse TiO(2) nanoparticles having an average particle size of 14.4?nm and predominant rutile phase were produced using a cluster-deposition technique without high-temperature thermal annealing and subsequently coated with uniform vinylidene fluoride oligomer (VDFO) molecules using a thermal evaporation source, prior to deposition as TiO(2)-VDFO nanocomposite films on suitable substrates. The molecular coatings on TiO(2) nanoparticles serve two purposes, namely to prevent the TiO(2) nanoparticles from contacting each other and to couple the nanoparticle polarization to the matrix. Parallel-plate capacitors made of TiO(2)-VDFO nanocomposite film as the dielectric exhibit minimum dielectric dispersion and low dielectric loss. Dielectric measurements also show an enhanced effective dielectric constant in TiO(2)-VDFO nanocomposites as compared to that of pure VDFO. This study demonstrates for the first time a unique electroactive particle coating in the form of a ferroelectric VDFO that has high-temperature stability as compared to conventionally used polymers for fabricating dielectric oxide-polymer nanocomposites.     

Multilayer self-assembly of TiO₂ nanoparticles and polyaniline-grafted-chitosan copolymer (CPANI) for photocatalysis

A photocatalytic thin film of TiO? nanoparticles and polyaniline-grafted-chitosan (CPANI) was fabricated by layer-by-layer (LbL) approach. The growth of the self-assembly of polymer nanocomposite was monitored by UV-vis spectroscopy and the thin film morphology was analyzed from scanning electron microscopy (SEM). Poly(styrene sulfonate) (PSS) was used as a bridging layer between TiO? nanoparticles and CPANI. Incorporation of CPANI within the LbL self-assembly of polymer nanocomposites enhanced the dye degradation ability of the thin film. These results indicate that the presence of CPANI improves the adsorption of dye in the self-assembly. The effect of surface area and the amount of catalyst was also examined. The reusability of the thin films for dye degradation study ensures the stability of the self-assembly.     

Enhanced electron transport in mesoporous TiO2 films modified by sol-gel necking for dye-sensitized solar cells

Mesoporous TiO2 films modified via sol-gel necking were fabricated by dispersing Ti tetra-isopropoxide (TTIP; 8 to 16 wt% over TiO2) with TiO2 nanoparticles in isopropyl alcohol. The dye-sensitized solar cells (DSSCs) with 13 wt% TTIP-modified TiO2 film exhibited significantly improved overall energy conversion efficiency, despite having less adsorbed dye when compared with DSSCs with untreated and TiCl4 post-treated TiO2 films. The improvement can be attributed to the sol-gel necking (or interconnection) between the nanoparticles which leads to a much faster electron transport and a suppression of the recombination (or back electron transfer) between the TiO2 and electrolyte.     

一种新型基于纳米TiO_2薄膜的电子纸器件(英文)

近年来,在电致变色领域基于甲基紫精修饰高比表面积的纳米TiO2薄膜电极取得了巨大的进步,并将这项技术推向商业化.本文介绍了一种由有机变色分子修饰纳米晶TiO2薄膜电极而组装成的电致变色器件,通过"嫁接"在甲基紫精分子上的磷酸基和纳米TiO2薄膜电极表面的羟基化学吸附,我们得到了具有良好电致变色性能的"电子纸".本文采用的电解质是0.05mol/L的高氯酸锂和0.05mol/L的二茂铁的1,4丁内酯溶液,对电极为透明导电玻璃.实验证明该电致变色器件具有很高的稳定性,并达到了毫秒级的响应速度,在未来显示领域"电子纸"的商业化进程中具有很大的潜力.     

聚乙烯亚胺改性TiO2及光催化性能研究

纳米TiO2经3-氨丙基三乙氧基硅烷(APTES)改性后,再通过聚乙烯亚胺(PEI)单体在APTES-TiO2表面进行原位化学氧化接枝聚合,制备了基于共价键结合的PEI/APTES-TiO2纳米复合光催化材料。以甲基橙(MO)为目标降解物,研究了所制备复合材料在紫外光下和太阳光作用下的光催化性能。通过红外光谱(FTIR)、X射线衍射(XRD)、透射电镜(TEM)等对所制备的复合材料进行了表征。结果表明,TiO2经过有机改性后复合材料在紫外光和太阳光下都出现了较强的吸收,光能的利用率和光生载流子的分离效率得到提高,复合材料表现出较高的光催化活性。     

Synthesis of a CNT-grafted TiO(2) nanocatalyst and its activity triggered by a DC voltage

Carbon nanotube (CNT)-grafted TiO(2) (CNT/TiO(2)) was synthesized as an electrically conductive catalyst that exhibits redox ability under electrical excitation besides ultraviolet (UV) irradiation. The CNT/TiO(2) material was synthesized by a two-step process. Ni nanoparticles were photodeposited onto TiO(2) first. The Ni nanoparticles then served as seeds for the growth of CNTs using the chemical vapor deposition (CVD) of C(2)H(2). The CNT/TiO(2) nanocomposite exhibits strong oxidation activity toward NO gas molecules via both photocatalysis under UV irradiation and electrocatalysis under a DC?voltage of 500?V in dark conditions.     

Diode behavior of electrophoretically deposited polyaniline on TiO2 nanoparticulate thin film electrode

An inorganic/organic hetrostructure diode was constructed by the electrophoretic deposition of the p-type polyaniline (PANI) on an n-type titanium oxide (TiO2) nanoparticulate thin film. The bonding and internalization of PANI to TiO2 nanoparticulate thin film were confirmed by the morphological, structural and optical studies of electrophoretically deposited PANI/TIO2 nanoparticulate thin film. The increased size of TiO2 nanoparticles indicated the well penetration of PANI molecules into the pores of mesoporous TiO2 nanoparticulate thin film. The XPS studies of PANI/TiO2 heterostructure exhibited the surface bonding and interaction between PANI molecules and TiO2 nanoparticles. The current-voltage (I-V) characterization of PANI/TiO2 heterostructure was carried out in the forward and the reverse bias at the applied voltage ranges from -1 V to +1 V with a scan rate of 2 mV/s. The constructed Pt/PANI/TiO2 heterostructure device established diodic behavior with non-linear nature of I-V curves.     

TiO2-Cu2O复合膜的制备及其可见光催化降解染料性能研究

采用电化学方法制备了TiO2-Cu2O纳米复合材料,并用喷涂法在玻璃表面制成TiO2-Cu2O复合膜.通过X射线衍射(XRD)、扫描电镜(SEM)等手段对TiO2-Cu2O复合材料进行了表征,用正交设计法研究了TiO2-Cu2O复合膜与Fe2 EDTA构成的Fenton试剂在可见光照射下催化降解亚甲基兰的性能,并用实验证实了H2O2存在.结果显示,TiO2-Cu2O复合膜光催化降解性能明显优于TiO2膜和Cu2O膜.与传统Fenton试剂相比,TiO2-Cu2O复合膜与Fe2 EDTA构成的Fenton试剂体系有效作用时间更长,并可重复使用.     

Photocatalytic decompositions of gaseous HCHO over Ag/TiO2 nanotube arrays

TiO2 nanotube arrays prepared by electrochemical anodization method attract considerable interest as a practical air purifier, as the nanotube arrays may form a TiO2 film with a porous surface and straight gas diffusion channel. Here, the TiO2 and Ag/TiO2 nanotube arrays with different Ag amount are used to degrade gaseous HCHO pollutants. The photocatalytic results confirm that the HCHO-degrading efficiency of the TiO2 nanotube arrays may vary with the amount of Ag nanoparticles, and the Ag amount within a certain range significantly improves the degradation rate of HCHO molecules. The main final product after HCHO degradation is detected to be CO2. Ag nanoparticles effectively act as electron trappers prohibiting the recombination of photo-excited electrons and holes, hence increasing the photocatalytic efficiency. However, excessive Ag nanoparticles form new recombination center of photo-excited electrons and holes to decrease the photocatalytic efficiency.     

纳米TiO2对不同材料超滤膜结构与性能的影响

选用聚醚酮(PEK)、聚醚砜(PES)、酚酞聚醚砜(PES-C)3种不同的高分子材料,用浸没沉淀相转化法制备了一系列不同纳米TiO2含量的纳米TiO2复合膜,并通过扫描电子显微镜(SEM),X射线能谱仪(EDS),水接触角测试及超滤实验考察了纳米TiO2对膜的结构及性能的影响.结果表明,纳米TiO2与高分子超滤膜的复合显著改善了膜的亲水性.在截留率较高且基本保持不变的情况下,3种超滤膜的纯水通量和BSA溶液通量都得到了不同程度的提高.而由EDS分析可知,经过一定的时间,膜表面的TiO2会部分脱落,TiO2粒子与膜表面结合的稳定性问题不容忽视.在选用的3种材料中,TiO2粒子与PES-C膜表面结合较为牢固,且复合后BSA溶液通量的增幅最大,通量衰减较小,具有更好的膜结构和性能.     

Facile preparation of Ag-coated TiO2 nanobelts and their photocatalytic activities

This article describes facile preparation of Ag nanoparticles coated on TiO2 nanobelts and their visible-light photocatalysis activity toward the degradation of Rhodamine B. An Ag complex was adsorbed onto the TiO2 nanobelts by impregnation of the nanobelts into an [Ag(NH3)2]NO3 aqueous solution, and subsequently the Ag precursor was reduced at room temperature by a glucose solution to form Ag nanoparticle-coated TiO2 nanobelts. The visible-light photodegradation of Rhodamine B on such nanocomposite was studied and showed much higher photocatalytic activity than commercial P-25 TiO2 nanoparticles and pure TiO2 nanobelts. Using a seeding preparation procedure through dropwise addition of fresh aqueous solution of NH2NH2 and AgNO3 alternately, larger Ag particles on TiO2 nanobelts were obtained.     

Effect of TiO2 particle size on the performance of viologen-anchored TiO2 electrochromic device

The effect of TiO2 particle size on the performance of the electrochromic device (ECD) has been investigated in this work by applying the TiO2 nanoparticles in 7, 15, and 30 nm sizes. The phosphonated viologen, bis(2-phosphonoethyl)-4,4'-bipyridinium dibromide, was anchored on the TiO2 surfaces for the construction of ECD. The ECD derived from 7 nm-sized TiO2 demonstrated the highest contrast ratio with high optical transparency, whereas it showed the slowest switching response. The enhancement of coloration efficiency with decrease of TiO2 particle size is due to the increased amount of the anchored viologen on TiO2 electrode. On the other hand, the relatively slower switching response would be caused by the difficulty of diffusion for the electrolytes and counter-ions through the small pores of the nanocrystalline TiO2 electrode derived from 7 nm-sized nanoparticles.     

聚吡咯/二氧化钛复合薄膜的制备及气敏性研究

运用静电力自组装和原位化学氧化聚合相结合的方法制备了聚吡咯/纳米二氧化钛(PPy/TiO₂)复合薄膜, 并进行了紫外－可见光谱分析和原子力显微镜分析. 采用平面叉指电极制备了PPy/TiO₂复合薄膜气体传感器, 研究了其在常温下对有毒气体NH₃和CO的敏感性. 最后测试了该传感器的温度湿度特性. 结果表明, 该传感器对NH₃具有较高的灵敏度, 对CO几乎没有响应. 同时讨论了复合薄膜沉积时间对气敏特性的影响, 实验表明当沉积时间为20min时, 该传感器的NH₃敏感特性最好.     

Analysis of the electron transport properties in dye-sensitized solar cells using highly ordered TiO2 nanotubes and TiO2 nanoparticles

This study uses TiO2 nanoparticles and highly ordered anatase TiO2 nanotubes (AOTnt) as thin film photoanodes for dye-sensitized solar cells (DSSCs). DSSCs are assembled by single-layer and double-layer films of photoanodes and their electron transfer performance is compared. TiO2 nanoparticles were fabricated by the sol-gel method, and AOTnts were grown on titanium foil. This study uses TiO2 nanoparticles or AOTnts to prepare single-layer photoanodes and TiO2 nanoparticles coated on an AOTnt film to fabricate double-layer photoanodes. These three different photoanodes are soaked in dye and assembled into DSSCs, and their open-loop voltage recession, electrochemical impedance, lifetime, life cycle, and effective diffusion coefficient are measured. Electron transfer efficiency of the photoanodes and light harvesting efficiency are further analyzed. The results show that the electron transfer efficiency, open-loop voltage recession, lifetime, life cycle, and effective diffusion coefficient of the DSSCs assembled using double-layer photoanodes (AOTnt-TiO2) are superior to those of single-layer photoanodes (TiO2 or AOTnt).     

MWCNTs/Cu(OH)2 nanoparticles/IL nanocomposite modified glassy carbon electrode as a voltammetric sensor for determination of the non-steroidal anti-inflammatory drug diclofenac

This paper describes the development and utilization of a new nanocomposite consisting of Cu(OH)₂ nanoparticles, hydrophobic ionic liquid 1-ethyl-3-methylimidazolium hexafluorophosphate (EMIMPF₆) and multiwalled carbon nanotubes for glassy carbon electrode modification. The nanocomposite was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM) along with energy-dispersive X-ray spectroscopy (EDX). The modified electrode was used for electrochemical characterization of diclofenac. Using differential pulse voltammetry, the prepared sensor showed good sensitivity and selectivity with low overpotential for the determination of diclofenac in the range from 0.18 to 119 μM, with a detection limit of 0.04 μM. Electrochemical studies suggested that the MWCNTs/Cu(OH)₂ nanoparticles/IL nanocomposite modified electrode provided a synergistic augmentation on the voltammetric behavior of electrochemical oxidation of diclofenac, which was indicated by the improvement of anodic peak current.     

丝网印刷法制备染料敏化太阳能电池光电性能的研究

采用水热法制备TiO2纳米颗粒,将获得的TiO2纳米颗粒制备成胶体,采用丝网印刷法在FTO表面刷涂制备染料敏化太阳能电池（DSSC）光阳极,通过扫描电子显微镜对电极表征和电池光电性能测试,探讨印刷层数及入射光强对DSSC光电性能的影响,实验结果表明,将制备的光阳极组装成电池后具有较好的光电性能,当印刷层数为8层、光强为80W／m2时,电池取得最好的光电性能。     

漆酚醛缩聚物/丙烯酸树脂/TiO2复合涂料的制备及性能

采用Sol-Gel法制备了漆酚缩甲醛聚合物/多羟基丙烯酸树脂/TiO2纳米复合涂料(UFP/MPA/TiO2),并用透射电镜、动态机械热分析、红外光谱和其它手段对复合涂膜进行测试。结果表明,TiO2以40 nm~80 nm的粒子均匀地分布于m(UFP)∶m(MPA)=5∶2的UFP/MPA聚合物基体中,且纳米TiO2粒子和聚合物间存在着较强的氢键。纳米TiO2粒子的引入,使得该复合涂膜具有比UFP或UFP/MPA涂膜更好的抗紫外线性能、常规物理力学性能和动态力学性能。     

Transparent nanocomposites of high refractive index based on epoxy resin and TiO2 nanoparticle

A stepwise sol-gel method for the synthesis of stable colloidal TiO2 using hydrolysis and condensation reactions of titanium tetraisopropoxide (TTP) was investigated. The surface modification was carried out using 3-glycidoxypropyltrimethoxysilane (GPTMS). The particle size range of the modified TiO2 observed by TEM was 3-8 nm. The nanocomposites based on an epoxy resin and the modified TiO2 showed strong UV absorption, but maintained high transmittance within the visible region. TEM images of the nanocomposites confirmed the homogenous and fine dispersion of the TiO2 nanoparticles in the epoxy resin. The refractive index of the nanocomposites increased linearly with increasing TiO2 content. With 60% TiO2 by weight, the transmittance and refractive index of the nanocomposite were 98.4% and 1.657, respectively.     

Ammonia sensing by hydrochloric acid doped poly(<Emphasis Type="Italic">m</Emphasis>-aminophenol)–silver nanocomposite

Processable poly(m-aminophenol) (PmAP) was synthesized using ammonium persulfate oxidant in 0.6 M sodium hydroxide solution at room temperature. Then, in situ PmAP–silver nanocomposite film was obtained by casting PmAP film from dimethyl sulfoxide with silver hydroxide ammonia mixture at 140 °C. The nanocomposite film was doped with hydrochloric acid (HCl) by general solution doping technique. The undoped and HCl-doped films were characterized by ultraviolet visible spectroscopy, Fourier transformed Infrared spectroscopy, transmittance electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction analysis. Spectroscopic characterizations confirmed that the PmAP was doped by silver nanoparticles and it was further doped by HCl used. So, the synthesized PmAP–silver nanocomposite showed a conductivity of 1.01 × 10⁻⁶ S/cm, which was increased to 3.27 × 10⁻⁴ S/cm after HCl doping. The well dispersed silver nanoparticles with average size 130–150 nm was observed by SEM and TEM analysis. Unlike conventional ammonia sensor here, the resistivity of the nanocomposite film was decreased on exposure to ammonia gas and the sensing properties of the HCl-doped nanocomposite films were also reproducible. It can be seen that the % response of doped nanocomposite was unchanged while, the response time was decreased with increasing ammonia vapor concentrations in air. The ammonia-sensing characteristics of the HCl-doped nanocomposite film was explained on the basis of a proposed mechanism.