Electrical and structural characterization of plasma polymerized polyaniline/TiO2 heterostructure diode: a comparative study of single and bilayer TiO2 thin film electrode

A heterostructure was fabricated using p-type plasma polymerized polyaniline (PANI) and n-type (single and bilayer) titanium dioxide (TiO2) thin film on FTO glass. The deposition of single and bilayer TiO2 thin film on FTO substrate was achieved through doctor blade followed by dip coating technique before subjected to plasma enhanced polymerization. To fabricate p-n heterostructure, a plasma polymerization of aniline was conducted using RF plasma at 13.5 MHz and at the power of 120 W on the single and bilayer TiO2 thin film electrodes. The morphological, optical and the structural characterizations revealed the formation of p-n heterostructures between PANI and TiO2 thin film. The PANI/bilayer TiO2 heterostructure showed the improved current-voltage (I-V) characteristics due to the substantial deposition of PANI molecules into the bilayer TiO2 thin film which provided good conducting pathway and reduced the degree of excitons recombination. The change of linear I-V behavior of PANI/TiO2 heterostructure to non linear behavior with top Pt contact layer confirmed the formation of Schottky contact at the interfaces of Pt layer and PANI/TiO2 thin film layers.     

Fabrication and characterization of polyaniline-znO hybrid nanocomposite thin films

Polyaniline (PANI)-ZnO nanocomposite thin film has been successfully fabricated on glass substrates by using vacuum deposition technique. The as-grown PANI-ZnO nanocomposite thin films have been characterized using X-ray diffraction, Scanning Electron Microscopy, Atomic Force Microscopy, UV-visible spectrophotometer and Fourier Transform Infrared (FTIR) spectroscopy, respectively. X-ray diffraction of as-grown film shows the reflection of ZnO nanoparticles along with a broad peak of PANI. The surface morphology of nanocomposite films has been investigated using scanning electron microscopy and atomic force microscopy. The hypsochromic shift of the UV absorption band corresponding to pi-pi* transition in polymeric chain of PANI and a band at 504 cm(-1) due to ZnO nanoparticles has been observed in the FTIR spectra. The hydrogen bonding between the imine group of PANI and ZnO nanoparticle has been confirmed from the presence of the absorbance band at 1151 cm(-1) in the FTIR spectra of the nanocomposite thin films.     

聚苯胺/TiO2复合纳米膜电极的制备及其光电性能

采用原位化学氧化法,在酸性TiO2溶胶中未加分散剂制备了聚苯胺修饰的TiO2稳定溶胶,并以涂刮法在柔性导电塑料薄膜上成膜。利用FT-IR、XRD、TEM、选区电子衍射、紫外-可见光谱、光电流-电压曲线对所制备的复合溶胶及复合膜进行了表征。结果表明TiO2与聚苯胺之间实现了结构上的复合,聚苯胺的引入改善了TiO2膜对太阳光的利用率,提高了TiO2膜的光电响应性能。这种用复合溶胶制备聚苯胺/TiO2复合膜的方式扩大了成膜基底的范围。     

TiO₂ photoanode structure with gradations in V concentration for dye-sensitized solar cells

V-TiO?(GC) photoanode film with graduated structure was prepared in a dye-sensitized solar cell work electrode by layer-by-layer method using TiO? precursor with gradations in V concentration on the indium tin oxide transparent conducting glass from substrate to surface. The effects of the gradient in V concentration on the structures and properties of TiO? photoanode film were discussed. The structure of the gradient V concentration has remarkable influence on the final performance of the DSSCs and I-V characteristic measurement indicates an enhanced efficiency by 31% as compared to pure TiO? nanoparticles film samples due to abundant solar light, fast injection and transmission velocity and the slowdown recombination of photoexcited electrons, simultaneously.     

复合电沉积制备SnO2/TiO2薄膜及其光电催化性能

为了寻求廉价、高效和稳定的光催化剂,用复合电沉积技术在紫铜片上制备了Sn/TiO2薄膜,经300℃热氧化使之形成SnO2/TiO2复合电极.利用SEM,XRD对薄膜进行了表征,以甲基橙为模型化合物,对复合电极的光催化和光电催化性能进行了测定.研究表明:该薄膜由0.3~1μm的颗粒构成,每个颗粒又由纳米晶粒形成;电极具有多孔结构,膜中的SnO2以两种不同的晶体结构存在;在薄膜质量相等的情况下,SnO2/TiO2薄膜的光催化活性是纯TiO2粒子膜的2.87倍;外加一定偏压下,其催化性能大幅度提高.     

Preparation and characterizations of polyaniline (PANI)/ZnO nanocomposites film using solution casting method

Polyaniline (PANI)-ZnO nanoparticles composites film has been successfully fabricated by solution casting technique on glass substrate in which ZnO nanopowder was prepared via auto combustion method and used as inorganic materials. The as-grown nanocomposites film has been characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Transmission electron microscopy (TEM) and Atomic Force Microscopy (AFM) for their structural and morphological characterizations. X-ray diffraction studies of as-grown film showed the reflection of ZnO nanoparticles along with a broad peak of PANI. The AFM study of the film shows the incorporation of ZnO nanoparticles into the polymer matrix which was further supported by roughness measurement. TEM images showed that the size of ZnO nanoparticles in the nanocomposites increase from ~ 35 nm to ~ 45 nm, indicating the interaction of nanoparticles with PANI molecular chains. FTIR spectra showed a band at 501 cm⁻¹ due to ZnO nanoparticles while the hydrogen bonding between the amine group of PANI and ZnO nanoparticles had been confirmed from the presence of the absorption band at 1148 cm⁻¹.     

Organic-inorganic hybrid materials based on polyaniline/TiO(2) nanocomposites for ascorbic acid fuel cell systems

Polyaniline was grafted onto a mixture of rutile and anatase TiO(2) nanoparticles by in situ chemical oxidative polymerization. These nanocomposites were characterized by carbon, hydrogen and nitrogen (CHN) analysis, x-ray diffraction (XRD), Fourier transform infrared (FTIR), ultraviolet-visible (UV-vis), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis. FTIR and UV-vis confirm the formation of polyaniline on TiO(2) nanoparticles. The TEM shows that the composites consist of PANI and TiO(2) nanoparticles. Compared to the neat polyaniline, PANI/TiO(2) composites show a higher capacitance and also a higher activity per mass of polyaniline. Since the PANI/TiO(2) composites are stable during the electrooxidation of ascorbic acid, they can be used as an alternative catalyst for direct ascorbic acid fuel cells.     

Enhancement of photovoltaic performance in dye-sensitized solar cells with the spin-coated TiO2 blocking layer

The TiO2 thin film layers were introduced with the spin-coating method between FTO electrode and TiO2 photoanode in dye sensitized solar cell (DSSC) to prevent electron back migration from the FTO electrode to electrolyte. The DSSC containg different thickness of TiO2 thin film (10-30, 40-60 and 120-150 nm) were prepared and photovoltaic performances were analysed with /-Vcurves and electrochemical impedance spectroscopy. The maximum cell performance was observed in DSSC with 10-30 nm of TiO2 thin film thickness (11.92 mA/cm2, 0.74 V, 64%, and 5.62%) to compare with that of pristine DSSC (11.09 mA/cm2, 0.65 V, 62%, and 4.43%). The variation of photoelectric conversion efficiency of the DSSCs with different TiO2 thin film thickness was discussed with the analysis of crystallographic and microstructural properties of TiO2 thin films.     

真空蒸发沉积聚苯胺—TCNQ复合薄膜的STM研究

利用扫描隧道显微镜对真空蒸发沉积的聚苯胺－ＴＣＮＱ（ＰＡＮＩ－ＴＣＮＱ）复合薄膜、纯聚苯胺薄膜及纯ＴＣＮＱ薄膜试样进行了对比分析。研究发现,纯ＰＡＮＩ薄膜和纯ＴＣＮＱ薄膜都是绝缘膜,而用ＴＣＮＱ挽杂获得具有较高导电特性的ＰＡＮＩ－ＴＣＮＱ复合薄膜。而且与表面粗糙不连续的ＰＡＮＩ薄膜和ＴＣＮＱ薄膜相比,ＰＡＮＩ－ＴＣＮＱ复合薄膜易形成较大面积的表面结构完善的连续膜。傅里叶变换红外光谱（ＦＴＩＲ）分析     

Ge/SiO2和Ge/ZnO/SiO2薄膜的磁控溅射制备及电学性能

采用射频磁控溅射方法以石英玻璃为衬底分别沉积制备出了Ge/SiO2和Ge/ZnO/SiO2薄膜。X射线衍射表明薄膜展示了明显的ZnO衍射峰和较弱的Ge衍射峰;傅里叶变换红外光谱曲线证明薄膜均具有各自的特征吸收峰;扫描电镜结果显示薄膜为颗粒状团簇结构,并且加入ZnO中间层可以有效的改善Ge层的质量。同时,对所得薄膜材料的电流-电压性能进行了研究,结果发现,Ge/SiO2薄膜的I-V曲线拟合后为斜线,相当于电阻;ZnO/SiO2薄膜为直线,可以认为是绝缘体;Ge/ZnO/SiO2薄膜在-10～10V之间电流电压呈线性关系,其电阻比Ge/SiO2薄膜小,当电压值超过15V之后,电流急剧增加而迅速使薄膜击穿,薄膜导通。     

Fabrication and characterization of transparent superhydrophilic/superhydrophobic silica nanoparticulate thin films

The realization of transparent and superhydrophilic/superhydrophobic surfaces by silica nanoparticulate thin films was exploited in this work. An aqueous electrostatic layer-by-layer assembly process was utilized to fabricate nanoparticulate thin films with adhesion/body/top layer structure on glass substrates by using SiO₂ nanoparticles and polyelectrolytes. The effects of volume ratio of differently sized silica nanoparticle solutions for the body layer deposition on transmittance in visible light region and surface wettability of the nanoparticulate thin films were systematically studied. The experimental results revealed that both optical transparency and superhydrophobicity/superhydrophilicity can be achieved on the same SiO₂ nanoparticulate thin film by using appropriate volume ratios of differently sized silica nanoparticle solutions for body layer deposition, and with and without silane treatment in the fabrication process. The high contrast of wettability that can be achieved by this way suggests the possibility of the creation of superhydrophilic/superhydrophobic patterning and superhydrophilic-superhydrophobic gradient on the same surfaces.     

TiO_2光阳极表面原位聚合聚苯胺的制备及表征

为有效解决染料敏化太阳能电池(DSSC)的固态电解质与光阳极界面接触差的问题,文中采用化学原位聚合法在染料敏化TiO2光阳极表面制备聚苯胺(PANI)导电膜,研究了PANI成膜的最佳工艺参数。通过微观形貌观察及电导率测试说明,低温条件用樟脑磺酸(CSA)掺杂PANI薄膜颗粒细小均匀,电导率高达6.297S/cm。红外光谱分析表明,用CSA掺杂PANI较盐酸掺杂的电荷离域更充分,掺杂效果更好。PANI/Dye-TiO2复合膜在可见光区的吸收峰增多,吸收频带增宽;最后通过DSSC电池性能测试得到以PANI为电解质的DSSC较液态DSSC开路电压高,短路电流低的结果。     

An electrochemical glucose sensor from an organically modified nanocomposite of viologen and TiO2

An organically modified TiO2 nanocomposite was explored for glucose detection. Bis-Butyl viologen (BBV) was mixed with TiO2 nanoparticles to generate highly dispersed nanocomposite solution, which provided organically modified nanocomposite film of TiO2 (BBV-TiO2). A transistor type sensor was fabricated using the BBV-TiO2 film and platinum gate electrode. The BBV-TiO2 nanocomposite sensor showed higher sensitivity to glucose sensing in low concentration region compared to that of TiO2 sensor. This result was ascribed to facilitated electron transport by the adsorbed viologen molecules on TiO2 nanoparticles, where viologen molecules act as an electron transfer mediator between enzyme and TiO2.     

Fabrication and characterization of photoelectrode thin films with different morphologies of TiO2 nanoparticles for dye-sensitized solar cells

This study deals with the fabrication of three different morphologies of TiO2 nanoparticles to fabricate two-layer photoelectrode thin film for dye-sensitized solar cells (DSSC). The four different TiO2 morphologies are titania nanotubes (Tnt), TiO2 nanoparticles (H220), TiO2 nanoparticle (SP) and commercial DP-25 nanoparticles (P-25). To prepare the thin films of the photoelectrodes, the first layer is coated by H220 TiO2 nanoparticles, and the second is coated by 3 kinds of materials optimally proportionally mixed - P25, SP and Tnt. The photoelectric conversion efficiency of DSSCs with photoelectrodes fabricated using H220 reached 6.31%. Finally, the TiO2 nanaomaterials with four different morphologies were used to prepare a two layer photoelectrode with the structure of H220/P25-Tnt-SP which was combined with a Pt counter electrode to assemble DSSCs. These DSSCs had photoelectric conversion efficiencies of as high as 7.47%.     

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。     

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.     

Single-Walled Carbon Nanotubes as a Chemical Sensor for SO2 Detection

Single-walled carbon nanotubes (SWNTs) are Introduced as a chemical sensor for the detection of sulfur dioxide (SO₂) molecules. For a single bundle of SWNTs, current-voltage (I-V) curves were measured for a series of different temperatures under adsorption of SO₂ molecules. The I-V characteristics for a "MAT"-type thin film SWNTs, with respect to the amount of SO₂ adsorbed, were measured at room temperature and compared directly with O₂ adsorption. The change in current upon the adsorption of SO₂ is distinctly higher than that of O₂, and is also reversible for adsorption and successive evacuation. Thus, the results strongly suggested that a thin film of SWNTs can be used as a chemical sensor in the nanometer scale devices.     

Electrical properties of a novel 1,3-bis-(p-iminobenzoic acid) indane Langmuir-Blodgett films containing ZnS nanoparticles

ZnS nanoparticles have been formed in a newly synthesized 1,3-bis-(p-iminobenzoic acid) indane (IBI) by exposing Zn2+ doped multilayered Langmuir-Blodgett (LB) film to H2S gas after the growth. The formation of ZnS nanoparticles in the LB film structure was verified by measuring UV-Visible absorption spectra. DC electrical measurements were carried out for thin films of IBI prepared in a metal/LB films/metal sandwich structure with and without ZnS nanoparticles. It was observed that ZnS nanoparticles in the LB films cause a blue-shift in the absorption spectra as well as a decrease in both capacitance and conductivity values. By analysing I-V curves and assuming a Schottky conduction mechanism the barrier height was found to be about 1.13 eV and 1.21 eV for IBI LB films without and with ZnS nanoparticles, respectively. It is thought that the presence of ZnS nanoparticles influences the barrier height at the metal-organic film interface and causes a change in electrical conduction properties of LB films.     

Synthesis and characterization of polyimide-based hybrid thin films from a novel colloidal core-shell nanocomposite particles

In this study, poly(4,4-(hexafluoroisopropylidenediphthalic anhydride)-co-oxydianiline) (6FDA-ODA) and a novel core-shell nanoparticle consisting of a core (SnO2/TiO2) and a shell (ZrO2/Sb2O3) with the composition (SnO2:TiO2:ZrO2:Sb2O3 = 18:5:3:4) were used to prepare polyimide/nanoparticles hybrid thin films. The resultant hybrid thin films were investigated by FTIR, TGA, DSC, TEM, SEM, AFM, alpha-step, UV-Vis, and n&k analyses. The results show that the prepared hybrid thin films had a good thermal stability. The size of nanoparticles was effectively controlled in the range of 8-10 nm in the hybrid thin films. These nanoparticles were evenly distributed across the hybrid thin films and no phase separation occurred. In terms of the optical properties, the prepared hybrid thin films had good transparency in the range of visible light. The cutoff wavelength had a blue shift as the content of the nanoparticles increased. The refractive index of prepared hybrid thin films increased with corresponding increases in nanoparticle content. Moreover, the prepared polyimide/core-shell nanoparticle hybrid thin films displayed excellent film formability and planarity.     

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.