P-Cu2O/n-ZnO nanowires on ITO glass for solar cells

In this paper, the fabrication and characterization of a heterojunction solar cell based on p-Cu2O/n-ZnO nanowires on ITO glass are presented. ZnO aligned nanocrystal seed layer is firstly prepared by RF magnetron sputtering technique, and then vertical ZnO nanowire arrays with an acicular crystal structure are obtained by using a chemical bath deposition processing. The results indicate that the ZnO nanowires with a diameter of about 50 nm and 500 nm in length can be easily obtained. The absorption and transmittance of the ZnO nanowires are studied. It is also noted that the Cu2O can fill well into the space between ZnO nanowires by an electrodeposition process. Furthermore, the effect of the Cu2O orientation on the cell performance is also presented.     

Direct growth of ZnO nanosheets on FTO substrate for dye-sensitized solar cells applications

ZnO nanosheets were directly grown on fluorine-doped tin oxide (FTO) substrate via simple solution process at low temperature by using zinc chloride and hexamethylenetetramine (HMTA). The morphological characterizations by SEM and TEM confirmed that the deposited structures are nanosheets in which some are assembled in flower-shaped morphologies. The detailed structural investigations revealed that the deposited nanosheets are pure and crystalline ZnO and composed of Zn and O only. The obtained ZnO nanosheets on FTO substrate were used as a photoanode to fabricate the dye sensitized solar cells (DSSCs). The fabricated DSSCs exhibited an overall light-to-electricity conversion efficiency of 1.45%. A short-circuit current of 4.51 mA/cm2, open-circuit voltage of 0.610 V, and a fill factor of 0.53 were achieved from the fabricated ZnO nanosheets-based DSSCs.     

Efficient field emission from vertically grown planar ZnO nanowalls on an ITO-glass substrate

Vertically grown planar ZnO nanowalls, with typical dimensions of 40-80?nm thickness and several micrometers wide, were electrodeposited on an indium-tin-oxide (ITO)-glass substrate at 70?°C. X-ray photoelectron spectroscopy (XPS) studies reveal that the nanowalls consist of ZnO covered with a Zn(OH)(2) overlayer. An x-ray diffraction (XRD) study shows that these nanowalls have the wurtzite structure and are highly crystalline. The corresponding Raman and photoluminescence spectra further indicate the presence of oxygen deficiency. These ZnO nanowalls exhibit excellent field emission performance, with not only a considerably lower turn-on field of 3.6?V?μm(-1) (at 0.1?μA?cm(-2)) but also a higher current density of 0.34?mA?cm(-2) at 6.6?V?μm(-1) than most ZnO nanowires and other one-dimensional nanostructures reported to date.     

A ZnO nanowire vacuum pressure sensor

In this study, we report the growth and characterization of lateral ZnO nanowires (NWs) on ZnO:Ga/glass templates. Using x-ray diffraction and micro-Raman spectroscopy, it was found that crystal quality of the as-grown ZnO NWs is good. It was also found that the average length and average diameter of the laterally grown ZnO NWs were 5?μm and 30?nm, respectively. A vacuum pressure sensor was then fabricated using a single NW bridging across two electrodes. By measuring the current-voltage characteristics of the samples at low pressure, we found that the currents were of 17, 34.28, 57.37 and 96.06?nA for the ZnO NW measured at 1 × 10(-3)?Torr, 1 × 10(-4)?Torr, 3 × 10(-5)?Torr and 5 × 10(-6)?Torr, respectively. These values suggest that the laterally grown ZnO NWs prepared in this study are potentially useful for vacuum pressure sensing.     

Fabrication of ultrathin Zn(OH)2 nanosheets as drug carriers

Ultrathin two-dimensional (2D) porous Zn(OH)2 nanosheets (PNs) were fabricated by means of one-dimensional Cu nanowires as backbones.The PNs have thickness of approximately 3.8 nm and pore size of 4-10 nm.To form "smart" porous nanosheets,DNA aptamers were covalently conjugated to the surface of PNs.These ultrathin nanosheets show good biocompatibility,efficient cellular uptake,and promising pH-stimulated drug release.     

镀锌钢板蒸镀镁层的耐腐蚀机理

采用真空蒸镀技术在镀锌钢板上蒸镀镁,制得了蒸镀镁层,将其在5%NaCl溶液中浸泡,运用XRD,SEM和电化学方法等对其腐蚀产物进行了分析.对2种材料的的腐蚀行为进行了研究,探讨了其耐腐蚀机理.结果表明:镀锌钢板蒸镀镁层是以MgZn2和Mg2Zn11.金属间化合物的形式存在;其腐蚀产物是以致密且具有良好绝缘性的ZnCl2·4Zn(OH)2·H2O和致密的Zn4CO3(OH)6·H2O为主体,而纯锌镀层的腐蚀产物是以疏松且具有N型半导体性质的ZnO为主体;蒸镀镁层的形成可以抑制Zn(OH)2向ZnO的转化,能促进Zn(OH)2向ZnCl2·4Zn(OH)2·H2O和Zn4CO3(OH)6·H2O的转化,后二者能够牢固地覆盖在基体表面,从而延缓了锌的腐蚀进程;在宏观上表现为镀锌钢板蒸镀镁层腐蚀产物相对于纯锌镀层更加致密,在电化学行为上表现为镀锌钢板蒸镀镬层具有更小的腐蚀电流和更高的极化电阻.     

All-solid,flexible solar textiles based on dye-sensitized solar cells with ZnO nanorod arrays on stainless steel wires

An all-solid, flexible solar textile fabricated with dye-sensitized solar cells (DSSCs) woven into a satin structure and transparent poly(ethylene terephthalate) (PET) film was demonstrated. A ZnO nanorod (NR) vertically grown from fiber-type conductive stainless steel (SS) wire was utilized as a photoelectrode, and a Pt-coated SS wire was used as a counter electrode. A graft copolymer, i.e. poly(vinyl chloride)-graft-poly(oxyethylene methacrylate) (PVC-g-POEM) was synthesized via atom transfer radical polymerization (ATRP) and used as a solid electrolyte. The conditions for the growth of ZnO NR and sufficient dye loading were investigated to improve cell performance. The adhesion of PET films to DSSCs resulted in physical stability improvements without cell performance loss. The solar textile with 10 × 10 wires exhibited an energy conversion efficiency of 2.57% with a short circuit current density of 20.2 mA/cm² at 100 mW/cm² illumination, which is the greatest account of an all-solid, ZnO-based flexible solar textile. DSSC textiles with woven structures are applicable to large-area, roll-to-roll processes.     

Metal organic chemical vapour deposition of vertically aligned ZnO nanowires using oxygen donor adducts

Vertically aligned zinc oxide (ZnO) nanowires (NWs) have been grown by liquid injection Metal Organic Chemical Vapour Deposition, using oxygen donor adducts of Me2Zn. The growth and characterisation of the nanowires grown using [Me2Zn(L)] where L = monodentate ethers, tetrahydrofuran (C4H8O) (1), tetrahydropyran (C5H10O) (2), furan (C4H4O) (3) and the bidentate ethers, 1,2-dimethoxyethane (C4H12O2,) (4) 1,4-dioxane (C4H8O2) (5) and 1,4-thioxane (C4H8SO) (6) is discussed. Single crystal X-ray structures of (4), (5), (6) have been established and are included here. The ZnO NWs were deposited in the absence of a seed catalyst on Si(111) and F-doped SnO2/glass substrates over the temperature range 350-600 degrees C. X-ray diffraction (XRD) data shows that the nanowires grown from all adduct precursors were deposited in the wurtzitic phase.     

Hydrothermal synthesis of phosphate-mediated ZnO nanosheets

ZnO nanosheets were obtained via a simple hydrothermal synthesis in the presence of sodium tripolyphosphate. The formation mechanism and effect of sodium tripolyphosphate concentration on the morphology of ZnO nanosheets have also been reported. Field emission scanning electron microscopy, transmission electron microscopy and fourier transform infrared spectroscopy were used to characterize the structure features and chemical compositions. The results show that the replacement of OH^? dangling bond on ZnO positive polar faces (0001) by PO₄^3? hinders splicing growth of [Zn(OH)₄]^2? growth units along the [0001] direction, which results in the formation of ZnO nanosheets.     

Ni—Zn—Fe氢氧化物的低温自发固相反应

摩尔比为Ni2＋：Zn2＋：Fe3＋：0．6：0．4：2．0的水溶液与OH-在气泡液膜中进行共沉淀反应,制得0．6Ni（OH）2（H2O）0.75·（0．4-n）Zn（On）2·2（1-m—n）Fe（OH）3·mFezO3·nZnFe2O4·xH2O前驱体,微结构为大量螺旋状分子簇和少量亚晶结构,用XRD检测结果表明,前驱体在室温放置10和14个月的转化产物是Fe2O3,ZnFe2O4和Nin6Znn．Fe2O4;放置55个月的主要产物是Nin6Znn4Fe2O4。提出了分子簇演绎氢氧化物脱水,优先生成Fe2O3晶核,亚晶结构演绎新生态氧化物分子自组装的低温自发固相反应机理。     

Low temperature growth and optical properties of ZnO nanowires using an aqueous solution method

ZnO nanowires were grown on indium tin oxide (ITO) coated glass substrates at a low temperature of 90 degrees C using an aqueous solution method. The ZnO seeds were coated on the ITO thin films by using a spin coater. ZnO nanowires were formed in an aqueous solution containing zinc nitrate hexahydrate (Zn(NO3)2 x 6H2O) and hexamethylenetetramine (C6H12N4). The pH value and concentration of the solution play an important role in the growth and morphologies of ZnO nanowires. The size of ZnO naonowires increased as the concentration of the solution increased. It was formed with a top surface of hexagonal and tapered shape at low and high pH values respectively. Additionally, the single crystalline structure and optical property of the ZnO nanowires were investigated using high-resolution transmission electron microscopy and photoluminescence spectroscopy.     

Growth of Zn(1_x)Mg(x)O and Zn(1_x)Cd(x)O nanowires and the application in light emitting devices

Magnesium and Cadmium doped ZnO nanowires were successfully grown by Chemical Vapor deposition method in a tube furnance. Photoluminescence spectra show that the band gap of ZnO nanowire has been tuned from 4.00 eV to 2.08 eV by Magnesium and Cadmium doping. Transmission Electron Microscopy and X-ray diffraction characterization analysis indicate that most of the formed nanowires are single crystalline with good quality. Zn(1-x)Cd(x)O nanowire sample was used for heterojunctional light emitting diode fabrication. Electroluminescence measurement yields a strong emission peak at 553 nm from the Zn(1-x)Cd(x)O nanowire.     

Influence of process variables on growth of ZnO nanowires by cathodic electrodeposition on zinc substrate

Influence of the deposition duration and electrolyte concentration on the structural and morphological features of the ZnO thin films, grown by cathodic electrodeposition on zinc substrate followed by annealing in air at 400 °C, have been investigated. The surface morphology of the as-synthesized films shows two distinct features, presence of ‘2-dimensional nanosheets’ on the area near the electrolyte-air interface and ‘granular’ nanostructures, below the interface region. However, upon annealing, the formation of ZnO nanowires, possessing length of several microns and diameter less than 20 nm, on the entire substrate is observed. The X-ray and selected area electron diffraction patterns clearly confirm the polycrystalline nature of the ZnO nanowires.     

The impact of morphology upon the radiation hardness of ZnO layers

It is shown that ZnO nanorods and nanodots grown by MOCVD exhibit enhanced radiation hardness against high energy heavy ion irradiation as compared to bulk layers. The decrease of the luminescence intensity induced by 130?MeV Xe(23+) irradiation at a dose of 1.5 × 10(14)?cm(-2) in ZnO nanorods is nearly identical to that induced by a dose of 6 × 10(12)?cm(-2) in bulk layers. The damage introduced by irradiation is shown to change the nature of electronic transitions responsible for luminescence. The change of excitonic luminescence to the luminescence related to the tailing of the density of states caused by potential fluctuations occurs at an irradiation dose around 1 × 10(14)?cm(-2) and 5 × 10(12)?cm(-2) in nanorods and bulk layers, respectively. More than one order of magnitude enhancement of radiation hardness of ZnO nanorods grown by MOCVD as compared to bulk layers is also confirmed by the analysis of the near-bandgap photoluminescence band broadening and the behavior of resonant Raman scattering lines. The resonant Raman scattering analysis demonstrates that ZnO nanostructures are more radiation-hard as compared to nanostructured GaN layers. High energy heavy ion irradiation followed by thermal annealing is shown to be a way for the improvement of the quality of ZnO nanorods grown by electrodeposition and chemical bath deposition.     

Synthesis and morphological studies of ZnCuTe ternary nanowires via template-assisted electrodeposition technique

ZnCuTe nanowires have been successfully synthesized via template-assisted one step electrodeposition technique from an aqueous solution of zinc sulphate (ZnSO₄·7H₂O), copper sulphate (CuSO₄·5H₂O) and tellurium oxide (TeO₂) at room temperature (303?K). Nanowires of diameter 200, 100 and 50?nm have been synthesized on copper and indium tin oxide coated glass substrates using track-etch polycarbonate membranes (Whatman). The morphologies and structures of electrodeposited ZnCuTe nanowires were characterized by Scanning electron microscopy (SEM) and X-ray diffraction (XRD). SEM confirmed the formation of nanowires and reveal that the morphologies of nanowires have diameter equal to the diameter of the templates used. The XRD pattern have shown a preferential growth of ZnCuTe nanowires along the (119) direction and the structure corresponding to hexagonal structure. Energy dispersive X-ray analysis confirmed that the zinc copper telluride nanowires are constituted of elements Zn, Cu and Te.     

Redox reaction-assisted growth of ZnO nanowires on SnO2 thin films

ZnO nanowires were grown onto SnO₂ film coated on Si substrate using a vapor transport method. Zn vapor was found to play important roles in reducing SnO₂ and in being oxidized as a ZnO layer. The growth mechanism of ZnO nanowires was revealed to be a two-step process of Zn-SnO₂ redox reaction and Sn catalyzed V-L-S (vapor-liquid-solid) growth; initially, Zn vapor atoms arriving at the SnO₂ surface reduce the SnO₂ to Sn and O atoms and diffuse into the SnO₂ layer to form a ZnO layer. The reduced Sn atoms diffuse out of the SnO₂ layer and are agglomerated to form Sn liquid droplets. Then, the Sn droplets on the surface of ZnO layer serve as a catalyst for the catalytic V-L-S growth of ZnO nanowires.     

PbS量子点/ZnO纳米片复合膜的制备及其光电化学性能

通过两步法合成PbS量子点(QDs)修饰ZnO纳米片复合膜. 首先利用电化学法在掺氟的SnO₂导电玻璃(FTO)上生长ZnO纳米片, 然后在ZnO纳米片上通过逐次化学浴法沉积PbS量子点形成PbS/ZnO复合膜. 利用扫描电子显微镜(SEM)、X射线衍射仪(XRD)详细表征了样品的表面形貌和晶体结构, 并研究了PbS/ZnO复合膜作为量子点敏化太阳能电池光阳极的紫外-可见吸收谱、光电化学性能和表面光电压谱. 对比ZnO纳米片经PbS量子点修饰前后, 发现PbS量子点修饰后光阳极的光吸收和光伏响应均从紫外区拓宽到了可见光区, 同时光电化学性能有了显著提高, 短路电流密度从敏化前的0.1 mA/cm²增加到0.7 mA/cm², 效率由0.04%增加到0.57%. 与单一ZnO纳米片相比, PbS/ZnO复合膜的表面光伏响应强度明显增强, 说明PbS与ZnO之间形成了有利于光生电荷分离的异质结, 从而导致了PbS/ZnO复合膜光电性能的增加.     

Controllable template synthesis of superconducting Zn nanowires with different microstructures by electrochemical deposition

A systematic study was conducted on the fabrication, structural characterization, and transport properties of Zn nanowires with diameters between 40 and 100 nm. Zinc nanowires were fabricated by electrodepositing Zn into commercially available polycarbonate (PC) or anodic aluminum oxide (AAO) membranes. By controlling the electrodeposition process, we found that the nanowires can be single-crystal, polycrystalline Zn, crystalline Zn/nanocrystalline ZnO composites, or entirely ZnO. The microstructure and chemistry was characterized by using transmission electron microscopy. Transport studies on single-crystal or polycrystalline Zn nanowire arrays embedded inside the membrane showed that the superconducting transition temperature, Tc, is insensitive to the nanowire diameter and morphology. The superconductivity shows a clear crossover from bulklike to quasi-1D behavior, as evidenced by residual low-temperature resistance, when the diameter of the wires is reduced to 70 nm (20 times smaller than the bulk coherence length).     

Dielectrophoretic fabrication and characterization of a ZnO nanowire-based UV photosensor

Wide-gap semiconductors with nanostructures such as nanoparticles, nanorods, nanowires are promising as a new type of UV photosensor. Recently, ZnO (zinc oxide) nanowires have been extensively investigated for electronic and optoelectronic device applications. ZnO nanowires are expected to have good UV response due to their large surface area to volume ratio, and they might enhance the performance of UV photosensors. In this paper, a new fabrication method of a UV photosensor based on ZnO nanowires using dielectrophoresis is demonstrated. Dielectrophoresis (DEP) is the electrokinetic motion of dielectrically polarized materials in non-uniform electric fields. ZnO nanowires, which were synthesized by nanoparticle-assisted pulsed-laser deposition (NAPLD) and suspended in ethanol, were trapped in the microelectrode gap where the electric field became higher. The trapped ZnO nanowires were aligned along the electric field line and bridged the electrode gap. Under UV irradiation, the conductance of the DEP-trapped ZnO nanowires exponentially increased with a time constant of a few minutes. The slow UV response of ZnO nanowires was similar to that observed with ZnO thin films and might be attributed to adsorption and photodesorption of ambient gas molecules such as O(2) or H(2)O. At higher UV intensity, the conductance response became larger. The DEP-fabricated ZnO nanowire UV photosensor could detect UV light down to 10?nW?cm(-2) intensity, indicating a higher UV sensitivity than ZnO thin films or ZnO nanowires assembled by other methods.     

Highly enhanced acetone sensing performances of porous and single crystalline ZnO nanosheets: high percentage of exposed (100) facets working together with surface modification with Pd nanoparticles

Porous and single crystalline ZnO nanosheets, which were synthesized by annealing hydrozincite Zn(5)(CO(3))(2)(OH)(6) nanoplates produced with a water/ethylene glycol solvothermal method, are used as building blocks to construct functional Pd-ZnO nanoarchitectures together with Pd nanoparticles based on a self-assembly approach. Chemical sensing performances of the ZnO nanosheets were investigated carefully before and after their surface modification with Pd nanoparticles. It was found that the chemical sensors made with porous ZnO nanosheets exhibit high selectivity and quick response for detecting acetone, because of the 2D ZnO nanocrystals exposed in (100) facets at high percentage. The performances of the acetone sensors can be further improved dramatically, after the surfaces of ZnO nanosheets are modified with Pd nanoparticles. Novel acetone sensors with enhanced response, selectivity and stability have been fabricated successfully by using nanoarchitectures consisting of ZnO nanosheets and Pd nanoparticles.