共查询到20条相似文献,搜索用时 0 毫秒
1.
Interest in creating tunable, ordered mesoporous materials based on surfactant supramolecular templating has been increasing over the last decade. For the production of film-type mesoporous materials, the most common method currently used is sol-gel based dip-coating method, which utilizes evaporation induced self-assembly (EISA) of surfactants. A more recently developed method, electrochemical interfacial surfactant templating, exploits the interfacial surfactant assembly formed on the working electrode to electrodeposit inorganic mesoporous films. This method offers mechanisms for inorganic wall construction and amphiphilic assemblies that are quite different from those of the sol-gel dip-coating method. As a result, it offers new possibilities to produce mesoporous films that cannot be produced by other means. This paper reviews the recent advances in producing and tuning lamellar structured mesoporous zinc oxide films via electrochemical interfacial surfactant templating. The general principles of this method will be explained in comparison with other methods used for producing mesoporous films. This will be followed by discussions of the key synthesis conditions that govern the repeat unit, quality, and orientation of lamellar structures constructed during electrodeposition. This review will provide a useful foundation to further develop electrochemical interfacial surfactant templating as a versatile method to produce a broader range of mesoporous films. 相似文献
2.
Kevin P. Musselman Talia Gershon Lukas Schmidt-Mende Judith L. MacManus-Driscoll 《Electrochimica acta》2011,(11):3758
An alternative water–ethanol zinc nitrate solution is demonstrated to completely eliminate macroscopic defects that are normally prevalent in ZnO films electrochemically deposited from aqueous zinc nitrate solutions. The inclusion of 25% ethanol (by volume) reduces the surface tension of the mixture and eliminates bubble formation on the conducting glass surface during deposition. To demonstrate the importance of film uniformity, the ZnO films are employed in ZnO–Cu2O n–p heterojunctions and an order of magnitude improvement in diode behaviour is observed. 相似文献
3.
A thermochemical study of the temperature effects on the Zn-Cl-H2O system by means of potential-pH, solubility and species repartition diagrams is presented with the view to better understand the effect of temperature on the deposition mechanism and composition of zinc oxide thin films. These calculations have been completed by film preparation at different temperatures between room temperature and 90 °C. Below 34 °C, we observe the absence of continuous film growth and surface passivation. The oxide nucleation and film growth start above 34 °C, whereas the optimum film transparency and crystallinity is obtained from 40 °C. Above, the main effect of the temperature is to raise the film texturation with the c-axis perpendicular to the substrate surface. 相似文献
4.
In this study, epitaxial ZnO films were grown hydrothermally on (1 1 1)-oriented single crystal MgAl2O4 substrates at 150 °C from aqueous precursor solutions. It was observed that the film morphology varied with the pH value of the precursor solution, giving pitted films at higher pH and smooth films at lower pH. The photoluminescence spectra of these ZnO films showed a strong near band-edge ultraviolet emission together with deep level emission bands comprised of green and orange-red luminescence. The green band centred around 500 nm was attributed to the presence of Zn vacancies, whereas the orange-red band centred around 650 nm could be related to the presence of oxygen interstitials. 相似文献
5.
In this paper the fabrication and the characterization of heterojunction solar cells based on electrodeposited ZnO and Cu2O is described. The effect of the electrodeposition conditions (pH and temperature) on the cell performance has been investigated. The cells made with a Cu2O layer deposited at high pH (12) and moderate temperature (50 °C) have shown conversion efficiency as high as 0.41%. 相似文献
6.
Seok-In Na 《Electrochimica acta》2008,53(5):2560-2566
Vertically aligned TiO2 nanotubes have been fabricated on the indium-doped tin oxide (ITO) by a simple and versatile technique using the electrochemically deposited ZnO nanorods, oriented along the c-axis, as a template in the spin-on based sol-gel reaction of a Ti precursor. The diameter, length, and shape of TiO2 nanotubes were controlled by changing the initial ZnO nanorod template and the spin conditions during sol-gel process of a Ti precursor. Scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) analysis, and X-ray diffraction (XRD) were used to confirm the successful formation of TiO2 nanotubes and characterize their structure and morphology. Furthermore, as an application of the TiO2 nanotubes, hybrid solar cells based on TiO2 and poly[2-methoxy,5-(2′-ethyl-hexyloxy)1,4-phenylenevinylene] (MEH-PPV) were successfully fabricated. 相似文献
7.
Pectin–ZnO nanocomposite was prepared in the aqueous solution condition at room temperature. The Fourier transform infrared,
X-ray diffraction, and transmission electron microscope (TEM) measurements confirmed the nanoscaled structure of pectin–ZnO
composite. According to the TEM observation, the average composite granules size was about 150 nm and the embedded ZnO nanoparticles
were uniform with an average diameter of 70 nm. 相似文献
8.
A novel high power symmetric ZnO/carbon aerogel composite electrode for electrochemical supercapacitor 总被引:1,自引:0,他引:1
We present, for the first time, a new material of symmetric electrochemical supercapacitor in which zinc oxide (ZnO) with carbon aerogel (CA) was used as active material. Physical properties of ZnO/CA composite were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). It was found that ZnO has single hexagonal structure and the grain size increases with increase of ZnO compository. The result of cyclic voltammetry indicates that the specific capacitance of ZnO/CA composite in 6 M KOH electrolyte was approximately 25 F/g at 10 mV/s for 2:1 composition. AC impedance analysis reveals that ZnO with carbon aerogel powder enhanced the conductivity by reducing the internal resistance. Galvanostatic charge/discharge measurements were done at various current densities, namely 25, 50, 75, and 100 mA/cm2. It was found that the cells have excellent electrochemical reversibility and capacitive characteristics in KOH electrolyte. The maximum capacitance of the ZnO/CA supercapacitor was 500 F/g at 100 mA/cm2. It has been observed that the specific capacitance is constant up to 500 cycles at all current densities, which implies that the dendrite formation was controlled. 相似文献
9.
Effect of pH on the morphology and optical properties of modified ZnO particles by SDS via a precipitation method 总被引:1,自引:0,他引:1
ZnO particles were synthesized directly from an aqueous solution of zinc acetate dihydrate in the presence of sodium dodecyl sulfate (SDS) and sodium hydroxide at 70 °C. The morphological changes were investigated in the range of pH 8-12. The hexagonal prism-like shape was formed at pH 8 and 10 by inhibition of growth along the c direction whereas the small rod-like shape was observed at pH 12. The estimated band gap and the room temperature photoluminescence intensity in a visible region are dependent upon the geometrical shape and size of the ZnO particles. 相似文献
10.
A novel type of ZnO nanowires-modified multiwalled carbon nanotubes (MWCNTs) nanocomposite (ZnO-NWs/MWCNTs) has been prepared by a hydrothermal process. The ZnO-NWs/MWCNTs nanocomposite has a uniform surface distribution and large coverage of ZnO nanowires onto MWCNTs with 3D configuration, which was characterized by scanning electron microscopy. Cyclic voltammetry and electrochemical impedance spectroscopy methods were applied to investigate the electrochemical properties of ZnO-NWs/MWCNTs nanocomposite. Surprisingly, unlike the conventional n-type semiconducting ZnO nanowires grown on Ta substrate, the ZnO-NWs/MWCNTs nanocomposite exhibits excellent electron transfer capability and gives a pair of well-defined symmetric redox peaks towards ferricyanide probe. What's more, the ZnO-NWs/MWCNTs nanocomposite shows remarkable electrocatalytic activity (current response increased 4 folds at 0.3 V) towards H2O2 by comparing with bare MWCNTs. The ZnO-NWs/MWCNTs nanocomposite could find applications in novel biosensors and other electronic devices. 相似文献
11.
Effects of preparing conditions on the electrodeposition of well-aligned ZnO nanorod arrays 总被引:1,自引:0,他引:1
By using a potentiostatic electrodeposition method, well-aligned ZnO nanorod arrays (ZNAs) were synthesized under different conditions. The effects of preparing conditions on the electrodeposition of ZNAs were systematically studied by scanning electron microscopy (SEM), X-ray diffraction (XRD) and absorbance spectroscopy. It is indicated that the electrodeposition parameters, such as electrodeposition potential, electrolyte pH, concentration of precursors, temperature of solution and electrodeposition time, have significant influence on the morphology, diameter, density and growth rate of ZNAs. The ZNAs, with well-defined crystallization, can be only obtained when the applied potential is controlled from −0.4 to −1.0 V. The growth temperature has great impact on the morphology of ZnO nanostructure but it is weakly related to the band gap (Eg) of ZNAs. The rod diameters can be monitored to some extent only by changing the concentration of the precursors. The electrolyte pH value has relative influence on the diameter of ZNAs. With the growth time increasing, ZNAs with high aspect ratio can be gained. 相似文献
12.
《Ceramics International》2021,47(21):29908-29918
The cellulose derived carbon/graphene/ZnO aerogel composite was prepared as an electrode in order to investigate the electrochemical properties. Carbon aerogel was synthesized using paper as an available cellulose source, and the composite was obtained through a new and simple preparation method including the immersion of monolithic carbon aerogel in graphene oxide/Zn2+ suspension and subsequent chemical reduction and freeze drying. The morphology, functional groups and crystalline structure of the samples were studied with Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Diffraction Spectroscopy (XRD), respectively. Electrochemical performance of the prepared binder free electrodes was examined using Cyclic Voltammetry (CV), Galvanostatic Charge-Discharge (GCD) and Electrochemical Impedance Spectroscopy (EIS). The data revealed that flexible carbon/graphene/ZnO composite resulted in a low density (0.035 g cm−3) electrode with the capacitance of 900 mF cm−2 at a high current density of 10 mA cm−2, lower IR drop and high cyclic stability (capacitance retention of 96%) after 1000 cycles, at 10 mA cm−2. These features were due to the presence of 3D porous conductive network, highly reduced graphene oxide, and the formation of ZnO nanoparticles on graphene sheets. Moreover, polyaniline (PANI) was introduced to carbon/graphene/ZnO composite electrode using electro-oxidation method at different reaction time and aniline concentration in order to achieve remarkably improved capacitance of 2500 mF cm−2 (at 10 mA cm−2) and low charge transfer resistance. Also, after the supercapacitor device assembly, the capacitance was retained. Based on the results, the synthesized composite is a promising material for new generation of lightweight freestanding electrodes with the high electrochemical performance. 相似文献
13.
14.
A method for electrochemical growth of homogeneous nanocrystalline ZnO thin films at room temperature 总被引:1,自引:0,他引:1
We report the electrodeposition at room temperature (25 °C), in a potentiostatic mode, of cohesive nanocrystalline ZnO thin films from an oxygenated zinc chloride bath. It is shown that the bath saturation by molecular oxygen precursor is a key parameter to grow the oxide at low temperature. After low O2 bubbling the solution is not saturated and the surface is more or less passivated by an amorphous Zn(OH)2 veil-like thin layer. After intense and long molecular oxygen bubbling, the current density rapidly increases after an induction period of about 800 s. At the foot of the current onset, crystallized ZnO seeds appear entrapped in the initial amorphous layer. The film nucleation is a delayed process. The electrode is subsequently covered by a homogeneous ZnO film with structures of several hundreds of nanometers in length composed of nanocrystals with size of about 17 nm. The room-temperature photoluminescence spectrum of the film is dominated by a strong UV emission at 3.25 eV due to the recombination of excitons. The visible emission centered at 2.36 eV, due to deep defects, is less intense than the UV one showing the good structural quality of the ZnO nanocrystallized film. The films have interesting properties to be used as a seed layer for instance. 相似文献
15.
Nanostructured thin films of lead sulfide have been synthesized by a new electrochemical approach based on the underpotential deposition (UPD) of Pb and S from the saturated solution of PbS containing excess of PbS particles as a source of Pb2+ and S2− at various temperatures.We have demonstrated that this new electrochemical route is a simple method with several advantages, including better control of the growth conditions and a one-step process to obtain the nanostructures of PbS. Scanning probe microscopy studies indicate that the growth of PbS nanofilms follows a two-dimensional layer-by-layer growth kinetics at the beginning of electrodeposition but a three-dimensional growth dominates after the formation of the first few layers. The results of morphological and structural investigations reveal that PbS nanostructures grown by this method are single-crystalline in cubic structure and have a preferential orientation along the [2 0 0] direction. The optical absorption spectra of PbS nanostructures show the blue-shift with respect to those of the bulk counterpart, which are attributed as quantum-size effect. 相似文献
16.
We report on electrodeposition of CdSe coatings onto ZnO nanowire arrays and determine the effect of processing conditions on material properties such as morphology and microstructure. CdSe-coated ZnO nanowire arrays have potential use in extremely thin absorber (ETA) solar cells, where CdSe absorbs visible light and injects photoexcited electrons into the ZnO nanowires. We show that room-temperature electrodeposition enables growth of CdSe coatings that are highly crystalline, uniform, and conformal with precise control over thickness and microstructure. X-ray diffraction and transmission electron microscopy show nanocrystalline CdSe in both hexagonal and cubic phases with grain size ∼5 nm. Coating morphology depends on electrodeposition current density. Uniform and conformal coatings were achieved using moderate current densities of ∼2 mA cm−2 for nanowires with roughness factor of ∼10, while lower current densities resulted in sparse nucleation and growth of larger, isolated islands. Electrodeposition charge density controls the thickness of the CdSe coating, which was exploited to investigate the evolution of the morphology at early stages of nucleation and growth. UV–vis transmission spectroscopy and photoelectrochemical solar cell measurements demonstrate that CdSe effectively sensitizes ZnO nanowires to visible light. 相似文献
17.
《Ceramics International》2016,42(3):4090-4098
Nanocrystalline ZnO–NiO mixed metal oxide powder has been successfully prepared via a simple homogeneous precipitation method in short time. The nanocrystalline sample was obtained at low calcination temperature (350 °C). Specific surface area, crystallite size and optical band gap of the samples depend on calcination temperature. The synthesized samples were characterized by means of powder X-ray diffraction, thermal gravimetric analysis, Fourier transform infrared spectroscopy, diffuse reflectance spectroscopy, surface area measurements, scanning electron microscopy coupled with energy dispersive X-ray analysis, transmission electron microscopy and magnetic measurements. The synthesized powder samples have been tested for their catalytic reduction of 4-nitrophenol to 4-aminophenol in the presence of sodium borohydride. 相似文献
18.
Han-Seul Kim Hyungeun Seo Kyungbae Kim Jaegab Lee Jae-Hun Kim 《Ceramics International》2018,44(15):18222-18226
ZnO is an important functional material, and a nanotube structure is beneficial for various applications. Here, we report the facile synthesis and electrochemical properties of carbon-coated ZnO nanotube materials as Li rechargeable battery anodes. ZnO nanorod was first synthesized via a simple hydrothermal method. Subsequently, the material was annealed with a carbon precursor, forming free-standing, carbon-coated ZnO nanotubes. The carbon-coated nanotube structure is beneficial to alleviate volume changes of the ZnO active material during Li insertion and extraction processes as well as to improve the electrochemical reaction kinetics. Electrochemical test results demonstrate that the carbon-coated ZnO nanotube electrodes deliver improved the cycling performance compared with ZnO nanorod electrodes. Better rate performance than carbon-coated ZnO nanoparticle electrodes was also achieved. 相似文献
19.
《Journal of the European Ceramic Society》2017,37(1):169-177
This paper presents a study of the precipitation of ZnO and CuO crystals during the sintering of Cu-doped Ni-Zn ferrites. The nature of the resulting crystal precipitates were analysed using scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) analysis, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), confirming the findings of a previous paper (Part I). This study examines the influence of sintering temperature and sintering time of the thermal cycle on their formation, and on their microstructure and electromagnetic properties. The same two consecutive chemical reactions proposed in Part I can be used to explain the bulk precipitation and subsequent re-dissolution of the zinc and copper oxides observed during sintering. The effect of these crystal precipitates on the final properties of this type of soft ferrite was also analysed, revealing a deterioration in its electromagnetic performance. 相似文献
20.
以Zn(Ac)2·2H2O、NaI和N2H4·H2O为原料,在未使用任何表面活性剂的简单水热反应体系中制得了ZnO纳米棒.采用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)对产物的晶体结构、形貌进行了表征分析,并对其光催化活性进行了探讨,以ZnO纳米棒为光催化剂对有机染料污染物甲基橙进行了光催化降解实验.实验结果表明,氧化锌纳米棒对甲基橙的光催化降解具有很好的催化作用,在紫外光照射120min后,对甲基橙的降解率接近完全. 相似文献