CdS修饰低密度TiO2纳米棒阵列复合膜的制备及光电性能

为了提高CdS光敏层在TiO₂一维纳米棒阵列中的填充率,在TiO₂种子层的基础上,采用水热法于FTO导电玻璃表面生长了棒长较短、棒间距较大的低密度TiO₂一维纳米棒阵列膜,通过化学浴沉积在TiO₂纳米棒表面包覆CdS种子层,以此为基底采用水热法于TiO₂一维纳米阵列中生长CdS光敏层。采用SEM,XRD及紫外-可见吸收光谱对不同CdS水热生长时间的TiO₂/CdS复合膜结构进行了表征,并对其光电性能进行了研究。结果表明,低密度TiO₂纳米棒阵列有利于CdS生长液在阵列中渗入形成完全包覆的CdS种子层,CdS光敏层通过水热过程在整个TiO₂纳米棒表面均匀生长,逐渐形成CdS对TiO₂纳米棒阵列的完全填充和包覆,并在阵列顶端形成由CdS纳米短棒组成的花状修饰层;CdS的修饰将TiO₂一维纳米阵列膜的光吸收拓展至可见光区,水热生长7 h所得到的TiO₂/CdS复合膜具有最高光电流。所制备的CdS修饰低密度TiO₂纳米棒复合膜在太阳电池器件中具有很好的应用前景。     

硫化镉/石墨烯/TiO_2纳米棒阵列的光电化学性能

采用水热法在掺氟导电玻璃(FTO)上生长TiO_2纳米棒阵列。通过电化学伏安法将氧化石墨烯还原并沉积在TiO_2纳米棒阵列上,再经过化学水浴沉积硫化镉,形成Cd S/石墨烯/TiO_2阵列复合材料。用X射线衍射仪、扫描电子显微镜及X射线能量色散仪对样品的晶型、形貌以及成分进行分析。通过电化学工作站表征样品交流阻抗、开路电位、光电流响应及光化学能转换效率。结果表明,复合材料的电荷转移电阻约是未修饰的TiO_2纳米棒阵列的1/17,光电流比未修饰的TiO_2纳米棒阵列提高约2.5倍,在外加电压为-0.6 V时可达到2.2%。     

水热法制备TiO2-ZnO纳米棒分级结构及其光电性能研究

为了增加光电极光生电子传输通道并提高其光敏剂的负载能力,采用两步水热法制备了一种新颖的TiO_2-ZnO纳米棒分级结构。采用水热法在FTO导电玻璃基底上生长TiO_2纳米棒有序阵列膜,通过浸泡提拉在TiO_2纳米棒上包覆一层ZnO溶胶,经烧结形成ZnO种子层;再次采用水热法于TiO_2纳米棒上生长ZnO纳米棒,形成TiO_2-ZnO纳米棒分级结构,通过旋涂辅助连续离子反应分别在TiO_2纳米棒阵列和TiO_2-ZnO纳米棒分级结构中沉积光敏剂CdS纳米晶,形成CdS/TiO_2纳米棒复合膜和CdS/TiO_2-ZnO纳米分级结构复合膜。利用SEM,TEM,XRD、紫外-可见吸收光谱、瞬态光电流图谱等表征和测试手段,对样品的形貌、结构、光吸收和光电性能进行了表征和测试。结果表明,与单纯的TiO_2纳米棒阵列相比,TiO_2-ZnO分级结构可以沉积更多的CdS光敏剂,CdS/TiO_2-ZnO纳米分级结构复合膜的光吸收性能和瞬态光电流均明显优于CdS/TiO_2纳米复合薄膜。凭借优异的光电性能,TiO_2-ZnO分级结构在太阳电池光阳极材料中具有很好的应用前景。     

Effect of TiO2 nanotubes lateral spacing on photovoltaic properties of dye-sensitized solar cells

Vertically aligned TiO2 nanotube arrays （-8 μm long, -110nm wide） have been fabricated through anodic oxidation of Ti-metal sheet in fluoride- containing electrolyte. By changing the volume ratio of ethylene glycol and diethylene glycol in the electrolyte, TiO2 nanotube arrays with different tube-to-tube lateral spacing, i.e., closely packed, just separated, and fully separated, have been synthesized and applied as photoanodes for dye-sensitized solar cells （DSSCs）. Photovoltaic efficiency of 2.99 %, 3.34 %, and 3.44 % has been obtained for DSSCs based on the closely packed, just separated, and fully separated TiO2 nanotube arrays, respectively, illustrating the effect of tube-to-tube lateral spacing of TiO2 nanotube arrays on the performances of DSSCs. It is suggested that fully separated TiO2 nanotube arrays are beneficial to the conversion efficiency of DSSCs due to higher dye loading and faster electron transfer.     

A review on TiO2 nanotube arrays: Fabrication, properties, and sensing applications

Fabrication, properties, and sensing applications of TiO₂ nanotubes have been reviewed, and the highly ordered TiO₂ nanotube arrays made by anodic oxidation in fluoride-contained electrolytes highlighted. The effect of anodization parameters (electrolyte, pH, and voltage) on the titania nanotube size and shape were discussed. The excellent biocompatibility of TiO₂, the high orientation, the large surface area with tunable pore sizes, as well as the high electron transfer rate along with the nanotubes make TiO₂ nanotube array an ideal substrate for the sensor’s fabrication and application. The sensors based on the TiO₂ nanotube arrays for sensing hydrogen, oxygen, humidity, glucose and hydrogen peroxide all exhibited low detection limit, high stability, very good reproducibility and high sensitivity.     

Au@SiO2 core/shell nanoparticle-decorated TiO2 nanorod arrays for enhanced photoelectrochemical water splitting

To improve the separation efficiency of photoinduced charge carries,Au@SiO2nanoparticles(NPs)with core–shell structure were loaded onto the surface of TiO2nanorods grown on fluorine-doped tin oxide substrate by a facile two-step process.The resulted Au@SiO2/TiO2photoanodes were characterized by X-ray diffraction,scanning electron microscopy,transmission electron microscopy,as well as photoelectrochemical measurements.Compared with pristine TiO2nanorod film,the Au@SiO2/TiO2films showed remarkable enhancement in photoelectrochemical water splitting,with incident photonto-current conversion efficiency increasing from 31%to37%at 380 nm at 0.7 V versus saturated calomel electrode.This could be interpreted by the effect of metallic surface plasmon resonance of Au@SiO2NPs,which would generate an intense electromagnetic field with spatially nonhomogenous distributed intensity.As a result,the charge carriers generated in the near-surface region of TiO2nanorods could be easily separated.This modification method based on the effect of metallic surface plasmon resonance for promoted charge carrier separation provides a promising way to develop semiconductor photoelectrodes with high solar water-splitting performance.     

CdTe包覆TiO2纳米棒壳核结构有序阵列与P3HT杂化太阳电池研究

采用水热法在含氟二氧化锡导电玻璃(FTO)上制备了有序的金红石型TiO2纳米棒阵列,在TiO2纳米棒阵列上电沉积CdTe纳米晶构成了CdTe包覆TiO2壳核式纳米棒阵列(CdTe/TiO2),然后将聚3-己基噻吩(P3HT)的氯苯溶液旋涂到CdTe/TiO2壳核式纳米棒阵列上构成P3HT包覆CdTe/TiO2壳核式纳米棒阵列的复合结构(P3HT/CdTe/TiO2),在P3HT/CdTe/TiO2壳核式纳米棒阵列复合结构上使用离子溅射法喷镀Au膜构制Au-P3HT/CdTe/TiO2结构的杂化太阳电池,实验测得以Au-P3HT/CdTe/TiO2结构组装的杂化太阳电池的能量转换效率为0.91%。     

Modification of TiO2 nanotubes arrays by CdS and their photoelectrocatalytic hydrogen generation properties

In order to realize hydrogen generation under visible light, novel CdS/TiO2 nanotubes arrays are developed by electrochemical anodizaUon of Ti in 0.15 mol/L NHTF ＋ 0.08 mol/L H2C2O4 electrolyte. The diameter of the nanotube is 80-100 nm and the length is approximately 550 nm. The CdS nano-particles are deposited on the TiO2 nanotubes arrays by chemical bath deposition （CBD） in the ammonia-thiourea system. A 300 W Xe lamp is used as the light source, CdS/TiO2 nanotube arrays are used as the photoanode with the application of 1.0 V bath voltage, and 0.1 mol/L Na2S ＋ 0.04 mol/L Na2SO3 solution is used as the electrolyte, then the rate of photoelectrocatalytic hydrogen generation is 245.4 μL/（h·cm^2）. This opens new perspectives for photoelectrocatalytic hydrogen generation by using CdS/TiO2 nanotubes arrays.     

Preparation of narrow band gap V2O5/TiO2 composite films by micro-arc oxidation

V₂O₅/TiO₂ composite films were prepared on pure titanium substrates via micro-arc oxidation (MAO) in electrolytes consisting of NaVO₃. Their morphology and elements were characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) analysis. Phase composition and valence states of species in the films were characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Ultraviolet-visible diffuse reflectance spectra (UV-Vis DRS) were also employed to evaluate the photophysical property of the films. The V₂O₅/TiO₂ composite films show a sheet-like morphology. Not only V₂O₅ phase appears in the films when the NaVO₃ concentration of the electrolyte is higher than 6.10 g/L and is loaded at the surface of anatase, but also V⁴⁺ is incorporated into the crystal lattice of anatase. In comparison with pure TiO₂ films the V₂O₅/TiO₂ composite films exhibit significantly narrow band gap energy. The film prepared in an electrolyte consisting of NaVO₃ with a concentration of 8.54 g/L exhibits the narrowest band gap energy, which is approximately 1.89 eV. The V₂O₅/TiO₂ composite films also have the significantly enhanced visible light photocatalytic activity. The film prepared in an electrolyte consisting of NaVO₃ with a concentration of 8.54 g/L exhibits the best photocatalytic activity and about 93% of rhodamine is degraded after 14 h visible light radiation.     

Structure and photocatalytic properties of TiO<Subscript>2</Subscript>-Graphene Oxide intercalated composite

TiO2-Graphene Oxide intercalated composite (TiO2-Graphene Oxide) has been successfully prepared at low temperature (80°C) with graphite oxide (GO) and titanium sulfate (Ti(SO4)2) as initial reactants.GO was firstly exfoliated by NaOH and formed single and multi-layered graphite oxide mixture which can be defined as graphene oxide,[TiO]2+ induced by the hydrolysis of Ti(SO4)2 diffused into graphene oxide interlayer by electrostatic attraction.The nucleation and growth of TiO2 crystallites took place at low temperature and TiO2-Graphene Oxide composite was successfully synthesized.Furthermore,the photocatalytic properties of TiO2-Graphene Oxide under the irradiation of UV light were also studied.The results show that the degradation rate of methyl orange is 1.16 mg min-1 g-1(refer to the efficiency of the initial 15 min).Compared with P25 powder,this kind of intercalation composite owns much better efficiency.On the other hand,the reusable properties and stable properties of TiO2-Graphene Oxide intercalated composite are also discussed in this paper.At last,crystalline structure,interface status,thermal properties and microscopic structure of TiO2-Graphene Oxide were characterized by X-ray diffraction (XRD),X-ray photoelectron spectroscopy (XPS),thermogravimetric analysis (TGA),field emission scanning electron microscopy (FESEM) and high-resolution Transmission Electron Microscopy (HRTEM).Also,we have analyzed major influencing factors and mechanism of the composite structures which evidently improve the photocatalytic properties.     

High conversion efficiency of pristine TiO<Subscript>2</Subscript> nanotube arrays based dye-sensitized solar cells

We prepared highly-ordered titanium dioxide nanotube arrays (TNAs) by anodizing Ti foils in F-containing electrolytes.The crystalline nature and morphology of the TNAs were studied using X-ray diffraction patterns and scanning electron microscopy.We found the morphology of TNAs affects the light-to-electricity conversion efficiency (η) of dye-sensitized solar cells (DSSCs).The efficiency of DSSCs reached 5.95% under the condition of light illuminated from the counter electrode.The high efficiency of TNA-based DSSCs was attributed to the neat top surface of TNAs,which allows more dye molecule loading on the surface of the TiO 2 nanotubes,and fewer electron recombination centers and a low interface resistance of integrated TNAs.     

Preparation of graphene and TiO2 layer by layer composite with highly photocatalytic efficiency

A process for fabricating graphene and TiO₂ layer by layer composite was introduced to improve the photocatalytic activity by controlling the layers, thickness and the mass ratio between graphene and TiO₂. The graphene oxide (GO) was synthesized from natural graphite powder by the modified Hummers method. Large-area uniform GO and TiO₂ thin films were made by a spin-coating process in turn. After exposure of the TiO₂/GO multilayer film to UV light irradiation which allows the reduction of GO to graphene, a novel photocatalytic structure as graphene and TiO₂ layer by layer composite was synthesized. The cross-sectional SEM image showed that a clear layer by layer microstructure with a single layer thickness of graphene or TiO₂ was in the range of about 50 nm. The total thickness of the film was around 5 μm which was varied according to the layer number of spin coating process. Raman spectra revealed that significant structural changes occurred through UV light irradiation. Photodegradation for methylene blue (MB) exhibited that the layer by layer composite is of higher photocatalytic activity than the pure TiO₂ layer.     

Fabrication and character ization of electrospun TiO2/CuS micro–nano-scaled composite fibers

A process to fabricate a kind of novel micro–nano scaled TiO2/CuS composite fibers by electrospinning technique and chemical precipitation method was developed in the present study. The microstructures and photoelectronic properties of the fibers were characterize d using SEM, FT-IR, UV–vis and fluorescence spectroscopy. The results revealed that the TiO2 portion in the composite fibers was a mixture rutile and anatase phases while TiO2 and CuS had been fully composite. The fibers had smooth surface with a diameter of 50–300 nm. Comparing with pure TiO2 fiber, the TiO2/CuS micro–nano-scaled composite fibers exhibited a strong absorption in the visible light region and the efficiency of photo-induced charge separation were enhanced. This composite system is of widely potential applications in the areas such as solar cells, supercapacity, photocatalysis, etc.     

Preparation of Zn-doped TiO2 nanotubes electrode and its application in pentachlorophenol photoelectrocatalytic degradation

Zn-doped titanium oxide （TiO2） nanotubes electrode was prepared on a titanium plate by direct anodic oxidation and immersing method in sequence. Field emission scanning electron microscopy （FESEM） showed that the Zn-doped TiO2 nanotubes were well aligned and organized into high density uniform arrays with diameter ranging from 50 to 90 nm. The length and the thickness were about 200 and 15 nm respectively. TiO2 anatase phase was identified by X-ray diffraction （XRD）. X-ray photoelectronspectroscopy （XPS） indicated that Zn ions were mainly located on the surface of TiO2 nanotubes in form of ZnO clusters. Compared with TiO2 nanotubes electrode, about 20 nm red shift in the spectrum of UV-vis absorption was observed. The degradation of pentachlorophenol （PCP） in aqueous solution under the same condition （initial concentration of PCP： 20 mg/L; concentration of Na2SO4：0.01 mol/L and pH： 7.03） was carried out using Zn-doped TiO2 nanotubes electrode and TiO2 nanotubes electrode. The degradation rates of PCP using Zn-doped TiO2 nanotubes electrode were found to be twice and 5.8 times as high as that using TiO2 nanotubes electrode by UV radiation （400 μw/cm^2） and visible light radiation （4500 μw/cm^2）, respectively. 73.5% of PCP was removed using Zn-doped TiO2 nanotubes electrode against 45.5% removed using TiO2 nanotubes electrode in 120 min under UV radiation. While under visible light radiation, the degradation efficiency of PCP was 18.4% using Zn-doped TiO2 nanotubes electrode against 3.2% using TiO2 nanotubes electrode in 120 min. The optimum concentration of Zn doping was found to be 0.909%. The PCP degradation efficiencies of the 10 repeated experiments by Zn-doped TiO2 nanotubes electrode were rather stable with the deviation within 3.0%.     

LaVO4/TiO2在分解甲基橙中的光催化性能研究

光催化剂TiO₂在污水有机物降解中有着巨大优势,但由于对光的利用率过低,需要在TiO₂的基础上进行掺杂来改善其光催化性能。本研究利用稀土镧元素对TiO₂进行了掺杂分别制备了LaVO₄/TiO₂和La(NO₃)₃/TiO₂复合光催化剂,并将它们应用于甲基橙的光催化降解反应,证实了LaVO₄对TiO₂的光催化效果有较明显的增强作用。另外还研究了不同pH条件制备和不同掺杂比例的LaVO₄/TiO₂光催化效果,pH在10.56左右制备出的LaVO₄和掺杂比例为5%的LaVO₄制得的LaVO₄/TiO₂复合光催化剂效果较好。     

Fabrication of Fe–TiC–Al2O3 composites on the surface of steel using a TiO2–Al–C–Fe combustion reaction induced by gas tungsten arc cladding

The aim of the present study was to fabricate Fe–TiC–Al₂O₃ composites on the surface of medium carbon steel. For this purpose, TiO₂–3C and 3TiO₂–4Al–3C–xFe (0 ≤ x ≤ 4.6 by mole) mixtures were pre-placed on the surface of a medium carbon steel plate. The mixtures and substrate were then melted using a gas tungsten arc cladding process. The results show that the martensite forms in the layer produced by the TiO₂–3C mixture. However, ferrite–Fe₃C–TiC phases are the main phases in the microstructure of the clad layer produced by the 3TiO₂–4Al–3C mixture. The addition of Fe to the TiO₂–4Al–3C reactants with the content from 0 to 20wt% increases the volume fraction of particles, and a composite containing approximately 9vol% TiC and Al₂O₃ particles forms. This composite substantially improves the substrate hardness. The mechanism by which Fe particles enhance the TiC + Al₂O₃ volume fraction in the composite is determined.     

Dielectric properties of low dielectric constant Ba0.60Sr0.40Mg0.15Ti0.85O3-Mg2TiO4 composite thin films for tunable applications

Ba0.60Sr0.40Mg0.15Ti0.85O3-xmol%Mg2TiO4 （x = 0-40 mol%） （BSTM-MT） composite thin films were fabricated by sol-gel method. The precursor solution of these composite thin films was prepared through mixing the Ba0.80Sr0.40Mg0.15Ti0.85O3 and Mg2TiO4 solution. The microstructures and dielectric tunability of composite thin films were investigated. The dielectric constant of composite thin films can be tailored from 155 to 55 by changing the concentration of Mg2TiO4. The dielectric loss of these composite thin films were still kept below 0.01 and the tunability was above 20% at a dc-applied electric field of 500 kV/cm. Suitable dielectric constant, low dielectric loss, and high tunability of this kind of composite thin films can be useful for potential microwave tunable applications.     

水热体系下二氧化钛与氧化石墨烯复合纳米晶的合成

 200 ℃下四方结构的二氧化钛(TiO2)与氧化石墨烯(GO)复合纳米晶在一个装有适量钛酸四丁酯、无水乙醇、氧化石墨烯和蒸馏水的密闭的水热釜中加热12 h后被制备。X射线粉末衍射仪（XRD)、扫描电子显微镜（SEM）、透射电子显微镜（TEM）等一系列分析仪器被运用来揭示二氧化钛与氧化石墨烯复合纳米晶是由粒径大约160 nm的四方结构的二氧化钛纳米晶与氧化石墨烯复合而成,通过紫外吸收对其光学性能进行了必要的测试。
     

Application of upconversion luminescence in dye-sensitized solar cells

An upconversion luminescence powder TiO2:(Er3+,Yb3+) is prepared by a hydrothermal method and used to fabricate dye-sensitized solar cell (DSSC).The TiO2:(Er3+,Yb3+) powder undergoes upconversion luminescence,converting infrared light which the dye can not absorb into visible light with wavelengths of 510-700 nm which the dye can absorb,increasing the photocurrent of the DSSC.TiO2:(Er3+,Yb3+) also acts as a p-type dopant,heightening the Fermi level of the oxide film,which increases the photovoltage of the DSSC.The best performance of the DSSC is found when the ratio of TiO2/luminescence powder is 1/3 in the luminescence layer.Under simulated solar irradiation of 100 mW cm-2 (AM 1.5),the DSSC containing TiO2:(Er3+,Yb3+) doping achieves a light-to-electricity energy conversion efficiency of 7.28% compared with 6.41% for the undoped DSSC.     

P3HT和Spiro-OMeTAD共混物作为光活性层的杂化太阳电池性能

为降低电荷复合率,提高杂化太阳电池的性能,将P3HT与Spiro-OMeTAD共混后的混合物作为光活性层和空穴传输层,旋涂在Sb_2S_3纳米粒子敏化的TiO_2纳米棒(TiO_2NR/Sb_2S_3)复合膜上,制备成杂化太阳电池。通过SEM、紫外可见吸收光谱、XRD、电化学阻抗图谱、稳态荧光光谱、J-V曲线等手段,对杂化太阳电池的微观结构、光电转换特性进行了表征和测试。结果表明:P3HT与Spiro-OMeTAD共混物比例为15 mg/1 mL时,得到结构为FTO/TiO_2NR/Sb_2S_3/P3HT:Spiro-OMeTAD/Ag杂化太阳电池的电荷负荷率低,电子生命长,能量转换效率达到了4.57%。所制备的杂化太阳电池性能优良,具有良好的应用前景。