TiO_2纳米管阵列的制备及其光电化学性质研究

以H3PO4/NH4F水溶液为电解液,在20V下阳极氧化钛片1h制得TiO2纳米管阵列,其管径约为100nm,管长约800nm。经不同温度煅烧后,利用FESEM、XRD和光电化学分析测试系统分别对纳米管阵列的形貌结构、晶相组成以及光电化学性质进行研究。光电化学特性研究结果表明600℃热处理后性能最佳。当前体系中所制备的薄膜结构上高度有序,光电化学性质优良,作为光电极材料在太阳能光电转换、光催化等领域具有广阔的应用前景。     

Structural,photoluminescence and photoelectrochemical properties of electrosynthesized ZnSe spheres

Zinc selenide (ZnSe) spheres have been successfully synthesized by a simple galvanostatic mode of electrodeposition method for the photoelectrochemical properties. These spheres are characterized for their structural and morphological features using X-ray diffraction studies, scanning electron microscopy techniques. The growth mechanism of the ZnSe spheres have been discussed in detail, which can be addressed as the 2H⁺ gas trap and cation exchange reaction. UV–vis absorption spectra revealed that an absorbance peak at 380 nm and its band gap energy was found to be ~2.57 eV. Photoluminescence measurement spectra revealed that, the spheres exhibit strong emission at 675.94 nm. The photoelectrochemical measurement of ZnSe spheres was studied and the calculated efficiency was found to be ~0.05 %. In the electrodeposition galvanostatic mode is good technique applicable for controlling the film thickness. Hence, these galvanostatically electrosynthesized ZnSe spheres could be used as a buffer layer in the photoelectrochemical solar cells.     

碘掺杂TiO_2薄膜电极制备和光电性能研究

以碘酸钾为碘源,钛酸丁酯为钛源,采用溶胶-凝胶法制备碘掺杂TiO2纳米粉体,采用旋涂法制成以ITO导电玻璃为基底的碘掺杂TiO2薄膜电极,并经300～600℃退火处理。采用XRD、XPS和紫外-可见吸收光谱等对样品微观结构、化学成分和光学特性进行表征,并对碘掺杂薄膜电极和纯TiO2薄膜电极的光电化学性能进行测定比较。结果显示少量碘掺入到TiO2,但经碘掺杂的TiO2紫外-可见光吸收限明显红移到可见光区（450～600nm之间）,碘掺杂TiO2薄膜电极经适当温度处理的光响应性比纯TiO2得到明显改善。     

Direct growth and photoelectrochemical properties of tungsten oxide nanobelt arrays

A single-step route was developed for the direct growth of tungsten oxide nanobelt arrays by heating a tungsten sheet without additional catalysts or reactants. X-ray diffraction and Raman analysis indicated that the tungsten oxide nanobelts were monoclinic. The surface photovoltage signal and photocurrent density of the tungsten oxide nanobelt arrays clearly suggested a high photoconversion ability. Further investigation demonstrated that the photoelectrocatalytic activity of the nanobelt arrays was higher than that of a tungsten oxide film when using phenol as the probe molecule.     

Ti doped hematite thin film photoanode with enhanced photoelectrochemical properties

Ti-doped Fe₂O₃ thin films were prepared on fluorine-doped SnO₂ substrate as visible light active photoelectrochemical anodes. The fabricated films were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscope (AFM), X-ray energy dispersive spectroscopy and X-ray photoelectron spectroscopy (XPS). XRD data showed all films exhibited rhombohedral hematite phase, and the cell parameters showed that Titanium atoms substituted Fe atoms in the hematite lattice. AFM demonstrated that Ti doping could decrease the particle size on the surface compared with pure hematite. XPS results presented that Ti atom concentration was about 2.23 % in the doped film surface. The incident photon to electron conversion efficiency of Ti doped α-Fe₂O₃ film reached 23 % at 400 nm under 0.30 V bias versus AgCl in 1 M NaOH, which was nearly four times than that of undoped film. Titanium atoms in α-Fe₂O₃ lattice could increase the conductivity of hematite film. And excited electrons and holes in the bulk film could be separated more efficiently, rather than recombining with each other rapidly as that in pure hematite, which ultimately prolonged the life of electrons and holes and obtained the high efficiency Fe₂O₃ photo anode.     

Structural, optical and photoelectrochemical properties of electrodeposited CdSe thin films

Cadmium Selenide thin films have been electrodeposited from an acidic bath using CdSO₄ as a cadmium source and SeO₂ as a selenium source at pH=3 on to stainless steel and fluorine-tin oxide coated glass substrates. The CdSe films have been characterized by X-ray diffraction, scanning electron microscopy and optical absorption. X-ray diffraction spectra showed that CdSe is polycrystalline with single hexagonal phase. The intensity of the (0 0 2) peak increases remarkably by annealing in nitrogen atmosphere. A microstructural study revealed that the films were uniform and well covered the substrate. Optical absorption studies showed that the bandgap of the CdSe is 1.70 eV. It is observed that the conductivity of the CdSe films increases by annealing in nitrogen atmosphere. The photoelectrochemical activities of CdSe films deposited on stainless steel and fluorine-tin oxide coated glass have been studied by using CdSe/ 1 M NaOH-1 M Na₂S-1 MS / C cell configuration and it is found that films deposited on stainless steel give better performance, photoelectrochemical (PEC) studies also reveal that the CdSe has n-type conductivity.     

Facile preparation and photoelectrochemical properties of CdSe/TiO2 NTAs

In the present work we report the design and synthesis of CdSe/TiO₂ nanotube arrays (NTAs) and their implementation as a photoanode for photoelectrochemical (PEC) application. CdSe nanoparticles with well dispersion were decorated on the inner and outer surfaces of 2.5 μm-long TiO₂ nanotubes via electrodeposition. These CdSe/TiO₂ NTAs exhibit a significant photocurrent responds under visible light illumination (λ ≥ 420 nm). The results presented in this study display a promising method that the photoelectrochemical performance could be improved via composition, size and crystalline control of CdSe/TiO₂ NTAs. And the tubular morphology is also able to facilitate charge transport in nanostructure-based PEC cells. This research demonstrates a new approach, which have great potential applications in fabricating novel heterostructure-photoelectrochemical devices.     

基底温度对三氧化钨薄膜光电化学性能的调控研究

由于环境友好性、高的地球丰度和稳定的物理化学性质,三氧化钨在光电响应、光催化领域应用潜力巨大,受到了人们的广泛关注.薄膜形态的光催化材料能够避免粉体材料的团聚问题,并且在转移、回收再利用方面优势明显,因此制备用于光催化的三氧化钨薄膜是当前的研究前沿.本文通过磁控溅射在石英玻璃基底上沉积三氧化钨薄膜,研究了不同基底温度对薄膜结构和形貌的影响.采用X射线衍射、X射线光电子能谱、场发射扫描电镜、紫外可见吸收光谱、电化学工作站、光催化自组装平台对薄膜的成分形貌、光电化学性能、光催化活性进行表征.测试结果表明:基底温度为500℃时制备的单斜相三氧化钨薄膜具有较好的结晶性和更少缺陷,在500℃的基底温度下,新出现的(002)晶面取向的晶粒导致薄膜表面粗糙度和表面能增加,提升了光生电子空穴分离效率.光降解实验进一步证实此条件下制备的样品表现出最佳的光降解效率.可见,基底温度对磁控溅射制备的三氧化钨薄膜的光电化学性能有明显的调控作用.     

Nanostructured carbon-doping anodic TiO2 from TiC and its photoelectrochemical properties

In this paper, nanostructured carbon-doped titanium dioxide (TiO(2-x)Cx) has been fabricated from titanium carbide (TiC) thin film using electrochemical anodization in a solution containing fluorine ion. The resulting samples were characterized via scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, X-ray diffraction (XRD), and photoelectrochemistry. The SEM images and EDX analysis indicated that a nanostructured thin film of carbon-doped titanium dioxide had been formed. The XRD pattern showed the structural change from TiC to anatase type TiO2 after annealing. A series of photoelectrochemical measurement showed an increase in photovoltage and in photocurrent for the electrode of anodized TiC sample. The results demonstrated the feasibility to process carbon doped nanostructured TiO2 through anodization promising for applications in high efficient photoelectrochemical conversion.     

Enhanced photoelectrochemical properties of TiO2 nanorod arrays decorated with CdS nanoparticles

TiO₂ nanorod arrays (TiO₂ NRAs) sensitized with CdS nanoparticles were fabricated via successive ion layer adsorption and reaction (SILAR), and TiO₂ NRAs were obtained by oxidizing Ti NRAs obtained through oblique angle deposition. The TiO₂ NRAs decorated with CdS nanoparticles exhibited excellent photoelectrochemical and photocatalytic properties under visible light, and the one decorated with 20 SILAR cycles CdS nanoparticles shows the best performance. This can be attributed to the enhanced separation of electrons and holes by forming heterojunctions of CdS nanoparticles and TiO₂ NRAs. This provides a promising way to fabricate the material for solar energy conversion and wastewater degradation.     

Chemically deposited TiO2/CdS bilayer system for photoelectrochemical properties

In the present investigation, TiO₂, CdS and TiO₂/CdS bilayer system have been deposited on the fluorine doped tin oxide (FTO) coated glass substrate by chemical methods. Nanograined TiO₂ was deposited on FTO coated glass substrates by successive ionic layers adsorption and reaction (SILAR) method. Chemical bath deposition (CBD) method was employed to deposit CdS thin film on pre-deposited TiO₂ film. A further study has been made for structural, surface morphological, optical and photoelectrochemical (PEC) properties of FTO/TiO₂, FTO/CdS and FTO/TiO₂/CdS bilayers system. PEC behaviour of FTO/TiO₂/CdS bilayers was studied and compared with FTO/CdS single system. FTO/TiO₂/CdS bilayers system showed improved performance of PEC properties over individual FTO/CdS thin films.     

Structural, compositional, thermoelectrical and photoelectrochemical properties of CdSe thin films

Cadmium selenide thin films have been deposited on non-conducting glass and stainless steel substrates. Films were characterized by X-ray diffraction, atomic absorption spectroscopy. The electrical and thermoelectrical properties also studied. The X-ray diffraction analysis shows that the film samples are in cubic crystal structure. Film was found to be cadmium deficient. The efficiency of photoelectrode was found to be 1.15 % using sulphide-polysulphide electrolyte.     

Synthesis, structure and photoelectrochemical properties of single crystalline silicon nanowire arrays

In the present work, n-type silicon nanowire (n-SiNW) arrays have been synthesized by self-assembly electroless metal deposition (EMD) nanoelectrochemistry. The synthesized n-SiNW arrays have been submitted to scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and optical studies. Initial probes of the solar device conversion properties and the photovoltaic parameters such as short-circuit current, open-circuit potential, and fill factor of the n-SiNW arrays have been explored using a liquid-junction in a photoelectrochemical (PEC) system under white light. Moreover, a direct comparison between the PEC performance of a polished n-Si(100) and the synthesized n-SiNW array photoelectrodes has been done. The PEC performance was significantly enhanced on the n-SiNWs photoelectrodes compared with that on polished n-Si(100).     

不同方法制备的TiO2薄膜电极光电性能比较

用Doctor-Blade和Dip-Coating方法制备了粒子膜和溶胶-粒子膜两类TiO2纳米晶薄膜电极,利用BAS—100B电化学工作站和IM-6e交流阻抗仪研究了两种电极的光电化学性能．由光电流和交流阻抗谱（EIS）的测试结果发现,由于引入溶胶,增加了TiO2纳米粒子与基底的附着力,改善了TiO2纳米粒子与基底以及TiO2纳米粒子之间的电性接触,使得溶胶-粒子膜电极的电荷转移电阻远远小于粒子膜电极,提高了溶胶-粒子膜电极的光电流．     

Preparation,electrical and photoelectrochemical properties of magnesium doped iron oxide sintered discs

Sintered discs of magnesium substituted iron oxides have been prepared by gel routes or classical solid state reaction techniques and their crystallographic, electrical, and photoelectrochemical properties examined. The discs, sintered between 1200 and 1400°C for 20 hours, contain both α-Fe₂O₃ and a spinel phase. The electrical properties of the discs have been correlated with spinel concentration, the electrical resistivity decreasing with increasing spinel content. The materials were found to be consistently n-type by Seebeck voltage measurements. Photoelectrochemical measurements in aqueous solution showed however that the sintered disc electrodes exhibit photocathodic currents that are characteristic of p-type semiconductors. Evidence is presented which suggests that inhomogeneities in the near surface region of the discs are responsible for the observed photoelectrochemical properties.     

Physico-chemical, photoelectrochemical and photocatalytic properties of electrodeposited nanocrystalline titanium dioxide thin films

Crystal structure and microstructural properties of titanium dioxide (TiO₂) thin films prepared by cathodic electrodeposition on indium-tin-oxide coated glass substrates from aqueous peroxo-titanium complex solutions have been investigated. The electrodeposited TiO₂ thin film electrode exhibited anodic photocurrent upon visible light irradiation, indicating the typical behavior of n-type semiconductor. The photodecomposition of CH₃CHO by such thin films on exposure to ultraviolet light illumination was also observed.     

Zn/纳米棒阵列ZnO/聚噻吩复合电极的制备及光电化学性质

使用简单的水热法在锌片上生长ZnO纳米棒阵列,并用电化学共聚制备了ZnO纳米棒阵列与聚噻吩(Zn/ZnO/PTH)复合膜。通过X射线衍射(XRD)、扫描电子显微镜(SEM)等手段对ZnO的结构和形貌进行表征,XRD结果表明产物为六方纤锌矿型ZnO。SEM结果表明,在垂直锌片方向生长了包括纳米棒、纳米片、纳米线的表面光滑的ZnO纳米阵列,其中以纳米棒为主,其直径为30～100nm,长度1μm。用光电流作用谱、光电流-电势图研究了Zn/ZnO/PTH电极的光电转换性质。结果表明,PTH修饰ZnO/Zn电极可使光电流产生波长发生明显红移,使其光电转换效率提高了4倍,填充因子FF=33%,光电转换效率η=1.25%。     

Synthesis and photoelectrochemical properties of thin bismuth molybdates film with various crystal phases

Bismuth molybdate films with various phase structures including α-Bi₂Mo₃O₁₂, β-Bi₂Mo₂O₉, γ-Bi₂MoO₆, and γ′-Bi₂MoO₆ are fabricated on the indium-tin oxide glass substrates from an amorphous heteronuclear complex via the dip-coating method by appropriate adjustment of the reaction conditions. α-Bi₂Mo₃O₁₂, β-Bi₂Mo₂O₉, and γ-Bi₂MoO₆ film can be obtained at 400 °C, 500 °C, and 500 °C for 1 h, respectively. At 500 °C, γ′-Bi₂MoO₆ can be obtained for 4 h. Film formation process is proposed based on the experimental results. Thin γ-Bi₂MoO₆ films exhibit high photoresponse under visible light irradiation. Incident photon to current conversion efficiency of thin γ-Bi₂MoO₆ film starts to increase near 450 nm. And, it can reach 4.1% at 400 nm. The top of the valence band and bottom of the conduction band are roughly estimated to be − 0.71 and 1.69 eV, respectively. In contrast, γ′-Bi₂MoO₆ generated weak photocurrent; α-Bi₂Mo₃O₁₂ and β-Bi₂Mo₂O₉ film has no photoresponse under visible light irradiation. The reason for the difference in the visible light response was discussed.     

Visible light photoelectrochemical performance of W-loaded TiO2 nanotube arrays: structural properties

Well aligned TiO2 nanotubes were successfully synthesized by anodization of Ti foil at 60 V in a fluorinated bath comprised of ethylene glycol with 5 wt% of NH4F and 5 wt% of H2O2. In order to enhance the visible light absorption and photoelectrochemical response of pure TiO2 nanotube arrays, a mixed oxide system (W-TiO2) was investigated. W-TiO2 nanotube arrays were prepared using radio-frequency (RF) sputtering to incorporate the W into the lattice of TiO2 nanotube arrays. The W atoms occupy the substitutional position within the vacancies of TiO2 nanotube arrays. The as-anodized TiO2 is amorphous in nature while the annealed TiO2 is anatase phase. The mixed oxide (W-TiO2) system in suitable TiO2 phase plays important roles in efficient electron transfers due to the reduction in electron-hole recombination. In this article, the effect of the sputtered W into the as-anodized/annealed TiO2 nanotube arrays on the photoelectrochemical response was presented.     

The effect of defects on some photoelectrochemical properties of semiconducting MgFe2O4

Undoped Magnesium Ferrite, when functioning as a photoanode in aqueous solution, shows a large transient current response; in contrast Sn-doped material shows no transients and has comparatively small photocurrents. This difference is correlated with the resistivities of the samples and is attributed to the presence of defects in the undoped material. The undoped material shows a photoresponse at 1.1 eV photon energy, well below the 2.18 eV bandgap of MgFe₂O₄. A comparison with the analogous properties of Fe₂O₃ is made.