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1.
Xiaojing Yang Fangyi Cheng Jing Liang Zhanliang Tao Jun Chen 《International Journal of Hydrogen Energy》2009,34(21):8785-8791
We report on PtxNi1−x (x = 0, 0.35, 0.44, 0.65, 0.75, and 0.93) nanoparticles as catalysts for hydrogen generation from hydrolysis of ammonia borane (NH3BH3). The PtxNi1−x catalysts were prepared through a redox replacement reaction with a reverse microemulsion technique. The structure, morphology, and chemical composition of the obtained samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) equipped with energy dispersive X-ray (EDX), and inductively coupled plasma emission spectroscopy (ICP). The results show that the diameters of the PtxNi1−x nanoparticles are about 2–4 nm, and the Pt atomic contents in the catalysts were 35%, 44%, 65%, 75%, and 93%, respectively. It is found that the catalytic activity toward the hydrolysis of NH3BH3 is correlated with the composition of the PtxNi1−x catalysts. The annealing of Pt0.65Ni0.35 at 300 °C for 1 h increases the crystallinity of the nanoparticles, but shows almost the same activity as that without annealing. Among the as-prepared PtxNi1−x nanoparticles, Pt0.65Ni0.35 displays the highest catalytic performance, delivering a high hydrogen-release rate of 4784.7 mL min−1 g−1 and a low activation energy of 39.0 kJ mol−1. 相似文献
2.
Chia-Ching Liao Fu-Rong Chen Ji-Jung Kai 《Solar Energy Materials & Solar Cells》2006,90(7-8):1147-1155
A simple method was developed to fabricate tungsten oxide (WO3−x) nanowires based electrochromic devices. The WO3−x nanowires are grown directly from tungsten oxide powders in a tube furnace. The WO3−x nanowires have diameters ranging from 30 to 70 nm and lengths up to several micrometers. The WO3−x nanowires based device has short bleach-coloration transition time and can be grown on a large scale directly onto an ITO-coated glass that makes it potential in many electrochromic applications. The structure, morphology, and composition of the WO3−x nanowires were characterized using the scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and energy-dispersive spectrometer. The optical and electrochromic performance of the nanowires layer under lithium intercalation was studied in detail by UV–VIS–NIR spectroscope and cyclic voltameter. 相似文献
3.
The n-CdZn(S1−xSex) and p-CuIn(S1−xSex)2 thin films have been grown by the solution growth technique (SGT) on glass substrates. Also the heterojunction (p–n) based on n-CdZn (S1−xSex)2 and p-CuIn (S1−xSex)2 thin films fabricated by same technique. The n-CdZn(S1−xSex)2 thin film has been used as a window material which reduced the lattice mismatch problem at the junction with CuIn (S1−xSex)2 thin film as an absorber layer for stable solar cell preparation. Elemental analysis of the n-CdZn (S1−xSex)2 and p-CuIn(S1−xSex)2 thin films was confirmed by energy-dispersive analysis of X-ray (EDAX). The structural and optical properties were changed with respect to composition ‘x’ values. The best results of these parameters were obtained at x=0.5 composition. The uniform morphology of each film as well as the continuous smooth thickness deposition onto the glass substrates was confirmed by SEM study. The optical band gaps were determined from transmittance spectra in the range of 350–1000 nm. These values are 1.22 and 2.39 eV for CuIn(S0.5Se0.5)2 and CdZn(S0.5Se0.5)2 thin films, respectively. J–V characteristic was measured for the n-CdZn(S1−xSex)2/p-CuIn(S1−xSex)2 heterojunction thin films under light illumination. The device parameters Voc=474.4 mV, Jsc=13.21 mA/cm2, FF=47.8% and η=3.5% under an illumination of 85 mW/cm2 on a cell active area of 1 cm2 have been calculated for solar cell fabrication. The J–V characteristic of the device under dark condition was also studied and the ideality factor was calculated which is equal to 1.9 for n-CdZn(S0.5Se0.5)2/p-CuIn(S0.5Se0.5)2 heterojunction thin films. 相似文献
4.
Ho Keun Song Soo Gil Kim Hyeong Joon Kim Suk Ki Kim Ki Wan Kang Jung Chul Leeand Kyung Hoon Yoon 《Solar Energy Materials & Solar Cells》2003,75(1-2):145-153
CuIn1−xGaxSe2 polycrystalline thin films were prepared by a two-step method. The metal precursors were deposited either sequentially or simultaneously using Cu–Ga (23 at%) alloy and In targets by DC magnetron sputtering. The Cu–In–Ga alloy precursor was deposited on glass or on Mo/glass substrates at either room temperature or 150°C. These metallic precursors were then selenized with Se pellets in a vacuum furnace. The CuIn1−xGaxSe2 films had a smooth surface morphology and a single chalcopyrite phase. 相似文献
5.
Fu-Kai Hsu Che-Wei Hsu Jeng-Kuei Chang Chih-Kuang Lin Sheng-Long Lee Cheng-En Jiang 《International Journal of Hydrogen Energy》2010,35(24):13247-13254
The effect of Ni-substitution on the structure and hydrogen storage properties of Mg2Cu1−xNix (x = 0, 0.2, 0.4, 0.6, 0.8, 1) alloys prepared by a method combining electric resistance melting with isothermal evaporation casting process (IECP) has been studied. The X-ray single-crystal diffraction analysis results showed that the cell volume decreases with increasing Ni concentration, and crystal structure transforms Mg2Cu with face-centered orthorhombic into Ni-containing alloys with hexagonal structure. The Ni-substitution effects on the hydriding reaction indicated that absorption kinetics and hydrogen storage capacity increase in proportion to the concentration of the substitutional Ni. The activated Mg2Cu and Mg2Ni alloys absorbed 2.54 and 3.58 wt% H, respectively, at 573 K under 50 bar H2. After a combined high temperature and pressure activation cycle, the charged samples were composed of MgH2, MgCu2 and Mg2NiH4 while the discharged samples contained ternary alloys of Mg–Cu–Ni system with the helpful effect of rising the desorption plateau pressures compared with binary Mg–Cu and Mg–Ni alloys. With increasing nickel content, the effect of Ni is actually effective in MgH2 and Mg2NiH4 destabilization, leading to a decrease of the desorption temperature of these two phases. 相似文献
6.
R. Chandramohan T. Mahalingam J. P. Chu P. J. Sebastian 《Solar Energy Materials & Solar Cells》2004,81(3):545
The electrodeposition of Zn1−xCdxSe polycrystalline semiconducting thin films from aqueous acidic bath without any additives onto tin oxide-coated conducting glass and titanium substrates are described. The influence of deposition parameters on the film formation and deposition mechanism based on cyclic voltammetry is discussed. X-ray diffraction studies showed the polycrystalline wurtzite nature for all the films deposited under the proposed conditions. The optical studies revealed the band gap values in the range between 2.82 and 1.72 eV as the film composition changes from ZnSe to CdSe. It has been observed that the concentration of cadmium salt plays an essential role on the alloy formation. The surface morphological studies and composition analysis were carried out and the results are discussed. 相似文献
7.
Sung Hyun Lee Akhlesh Gupta ShanLi Wang Alvin D. Compaan Brian E. McCandless 《Solar Energy Materials & Solar Cells》2005,86(4):551-563
Cd1−xZnxTe alloy films with 1.6 and 1.7 eV band gaps were deposited by RF magnetron sputtering from targets made either of mixed powders or alloys of CdTe and ZnTe (25% and 40%). High-quality polycrystalline films with the (1 1 1) preferred orientation were obtained. The films were characterized using X-ray diffraction (XRD), scanning electron microscopy, resistivity, optical absorption, Raman, and photoluminescence. The EDS, XRD, and optical absorption analysis indicated that the x-value of the as-grown films were typically 0.20 and 0.30 for films sputtered from 25% and 40% ZnTe containing targets, respectively. The as-deposited alloy films exhibit quite low photovoltaic performance when used to make cells with CdS as the hetero-junction partner. Therefore, we have studied various post-deposition treatments with vapors of chlorine-containing materials, CdCl2 and ZnCl2, in dry air or H2/Ar ambient at 390 °C. The best performance of a Cd1−xZnxTe cell (, ) was found for treatment with vapors of the mixed CdCl2+0.5%ZnCl2 in an H2/Ar ambient after pre-annealing at 520 °C in pure H2/Ar. 相似文献
8.
Cd-rich CdxHg1 − xTe films have been electrodeposited under potentiostatic conditions on conducting glass and Ti substrates from an acidic solution containing the respective ions as Cd2+:Hg2+:HTeO2+ = 100:1:2. Six films one after another have been prepared from a single electrochemical cell. EDAX analysis of the air annealed films show decreasing Hg content in the deposit as the number of film preparation increases. SEM analysis indicate undulatory surface with Hg-rich clusters at the top surface. XRD analysis indicate the presence of CdxHg1 − xTe along with
. The CdxHg1 − xTe alloy formation have been confirmed from Raman shift measurements which change with composition, x. The as-deposited films are n-type but converts to p-type after air annealing. Spectral response measurements gave band gap values that change with Hg content in the deposit. Band gap values ranging from 1.1 eV to 1.45 eV have been estimated. Photoelectrochemical solar cells using polysulphide electrolyte have been fabricated which gave an open-circuit photovoltage and short-circuit photocurrent, respectively, as 325 mV and 5.5 mA/cm2 under 60 mW/cm2 intensity of illumination. 相似文献
9.
Chia-Ching Liao Fu-Rong Chen Ji-Jung Kai 《Solar Energy Materials & Solar Cells》2007,91(13):1258-1266
The effect of thermal annealing on the electrochromic properties of the tungsten oxide (WO3−x) nanowires deposited on a transparent conducting substrate by vapor evaporation was investigated. The X-ray diffraction (XRD) indicated that the structures of the nanowries annealed below 500 °C had no significant change. The X-ray photoelectron spectroscopy (XPS) analysis suggested that the O/W ratio and the amount of W6+ ions in the annealed nanowire films could be increased as increasing annealing temperature. Increased annealing temperature could promote the coloration efficiency and contrast of the nanowire films; however, it could also affect the switching speed of the nanowire films. 相似文献
10.
CdO and Cu2O thin films have been grown on glass substrates by chemical deposition method. Optical transmittances of the CdO and Cu2O thin films have been measured as 60–70% and 3–8%, respectively in 400–900 nm range at room temperature. Bandgaps of the CdO and Cu2O thin films were calculated as 2.3 and 2.1 eV respectively from the optical transmission curves. The X-ray diffraction spectra showed that films are polycrystalline. Their resistivity, as measured by Van der Pauw method yielded 10−2–10−3 Ω cm for CdO and approximately 103 Ω cm for Cu2O. CdO/Cu2O solar cells were made by using CdO and Cu2O thin films. Open circuit voltages and short circuit currents of these solar cells were measured by silver paste contacts and were found to be between 1–8 mV and 1–4 μA. 相似文献
11.
Polycrystalline thin films of AgxGa2−xSe2 (0.4x1.6) were prepared onto cleaned glass substrates by the stacked elemental layer (SEL) deposition technique. All the films were annealed in situ at 300 °C for 15 min. The compositions of the films were measured by energy-dispersive analysis of X-ray (EDAX) method. The structural and optical properties of the films were ascertained by X-ray diffraction (XRD) and UV–VIS–NIR spectrophotometry (photon wavelength ranging from 300 to 2500 nm), respectively. The influence of the composition on the optical properties of the material has been investigated. Microstructural perfection is quite evident from the abrupt descent around specific energy of photons in the transmittance spectra. Stoichiometric or slightly silver-deficient films show optimum electron transition energy and minimum sub-band gap absorption. 相似文献
12.
CdSe0.3Te0.7 alloy was prepared from the individual components and its composition and structural analysis were done. Films were prepared by hot wall deposition technique using 0.15 m length tube under a vacuum of 5×10−5 Torr on well cleaned glass substrates. The composition, structural, morphological, and optical properties of hot wall deposited films were investigated. The XRD analysis revealed that the films are like amorphous in nature for lower thicknesses but with increasing thickness a more preferred orientation along (1 0 1) direction was observed. The crystallite size (D), dislocation density (δ) and strain () were evaluated. From the EDX composition analysis, the individual concentrations of Se and Te in the films were estimated. An analysis of optical measurements shows that all the films have fairly good transparency above 850 nm. The optical band gap was found to be around 1.55 eV and decreases with increasing thickness. Also comparison of band gap with corresponding values for CdSe and CdTe are made. 相似文献
13.
NiOxHy films were prepared by DC magnetron sputtering in H2/O2 atmosphere. NiOxHy coatings with transparency and high electrochromic efficiency were obtained by changing H2 content. A 60 nm thick NiOxHy film with transmittance of 0.57 (as-deposited state), 0.78 (bleached state) and 0.24 (coloured state) at wavelength of 550 nm was deposited in an atmosphere of H2(60%)+O2(40%). Analysis of infrared spectra (60002400 cm−1) showed that the absorption peaks for bleached and colored states are associated with free ‘OH’ and OH stretching vibrations, respectively. XPS Ni2p core level spectra of colored NiOxHy film exhibited a peak at 856.2±0.2 eV which is attributed to Ni3+. Ni2p core level spectra of the bleached and as-deposited films exhibited two peaks at 856.4±0.2 and 854.6±0.2 eV which are attributed to Ni3+ and Ni2+. 相似文献
14.
Electrochromic films of NiOx and WOxPy were produced by the spray pyrolysis technique. The nickel-oxide-based coatings were obtained from both an alcoholic solution of nickel nitrate and aqueous solution of the mixture nickel nitrate/cobalt nitrate. Coatings obtained from alcoholic solutions showed a noticeable contrast of optical transmittance from fully bleached to colored state. X-ray diffraction analysis showed a slight crystallization in NiOx after electrochemical treatment: one diffraction peak for as-deposited films turned to three diffraction peaks for electrochemical treated samples. Coatings obtained from aqueous solution of mixture nickel nitrate/cobalt nitrate showed an optimized electrochromic behavior at a Ni:Co proportion of 90:10. At this condition an optical contrast of 50% is found. X-ray diffraction showed that these samples comprised a phase mixture of Co3O4 and NiO.WOxPy samples were obtained from polytungsten gel in which H3PO4 was added. We found that for 8.3 at% of P:W, the electrochromism was optimized. Pyrolytic coatings of WOxPy show superior behavior than those of WOx obtained by spray pyrolysis, both in optical contrast and durability. 相似文献
15.
A series of BiWxV1−xO4+x/2 films were coated on fluorine-doped tin oxide (FTO) glass by a polymer-assisted method and examined as photoelectrodes for photoelectrochemical measurements under Xe lamp light irradiation in a 0.5 M Na2SO4 solution. The compositions, structural, optical and morphologic properties of the films were characterized by XPS, XRD, UV–vis and SEM. The results showed the successfully synthesized films and their photoelectrochemical activities, revealing that the amount of tungsten had an important effect on the photoelectrochemical activities of BiWxV1−xO4+x/2 films and the highest incident photon to current conversion efficiency (IPCE) was obtained when x equaled 0.1. 相似文献
16.
The effect of the growth temperature and Mg/(Mg+Zn) molar flow rate ratio of metal organic sources on the crystalline structure of Zn1−xMgxO (ZMO) films is investigated in thin films prepared by metal organic chemical vapor deposition (MOCVD) process on fused silica in order to obtain the wide-bandgap ZMO films with single wurtzite structure, which is very important to achieve high-efficiency chalcopyrite solar cells. Based on the measurements and analysis of the fabricated samples, the ZMO films with the controllable bandgap from 3.3 to 3.72 eV can exhibit a single wurtzite phase depending on the growth temperature and Mg content. Furthermore, the resistivity of ZMO films is comparable to that of ZnO film. It is a good indication that ZMO film is superior to CdS or ZnO films as buffer and window layers mainly due to its controllable bandgap energy and safety. As a result, the solar cells with ZMO buffer were fabricated without any surface treatment of Cu(InGa)(SSe)2 (CIGSSe) absorber or antireflection coating, and the efficiency of 10.24% was obtained. 相似文献
17.
The full composition range CuIn(SxSe1−x)2 alloy system has been studied using 40 mm length crystal cuts from 10 mm diameter ingots grown by the classical Bridgman method. X-ray diffraction diffractographs show that the CuIn(SxSe1−x)2 compounds have a chalcopyrite structure for each composition x, they exhibit an expansion on the unit cell characteristics by the tetragonal distortion which depends linearly on the electronegativity of the atoms. The photoluminescence spectra is investigated as a function of various compositions, temperature and excitation intensities. Photoluminescence spectra shows a wide variation in the dominant peak location and an overall blue shift with the increase of sulphur content. Photoluminescence CuInS2 and CuIn(S0.72Se0.28)2 have been studied in detail. 相似文献
18.
S. Bao K. Tajima Y. Yamada M. Okada K. Yoshimura 《Solar Energy Materials & Solar Cells》2008,92(2):224-227
In this paper, we show gasochromic and electrochromic switching properties of Pd top capped magnesium–titanium (Mg–Ti) thin films prepared by DC magnetron sputtering. These films show excellent switchable mirror properties. By exposing to 4% H2 in Ar, Pd (4 nm)/Mg0.82Ti0.18 (40 nm) film changed from the metallic state to the transparent state drastically within 5 s. By exposing to air, it goes back to the metallic state within 60 s. The transmittance spectrum in the hydride state is quite flat in the wavelength range from 400 to 2500 nm. It looks complete color neutral and its chromaticity coordinates are x=0.326 and y=0.340. Simple electrochromic device of Mg–Ti thin film using a liquid electrolyte works very well. It can be switched between the mirror state and the color-neutral transparent state. 相似文献
19.
Shin-ichi Shimakawa Yasuhiro Hashimoto Shigeo Hayashi Takuya Satoh Takayuki Negami 《Solar Energy Materials & Solar Cells》2008,92(9):1086-1090
Annealed Zn1−xMgxO/Cu(In,Ga)Se2 (CIGS) interfaces have been characterized by ultraviolet light excited time-resolved photoluminescence (TRPL). The TRPL lifetime of the Zn1−xMgxO/CIGS film increased on increasing the annealing temperature to 250 °C, whereas the TRPL lifetime of the CdS/CIGS film had little change by annealing at temperatures lower than 200 °C. This is attributed to the recovery of physical damages by annealing, induced by sputtering of the Zn1−xMgxO film. The TRPL lifetime abruptly decreased with annealing at 300 °C. The diffusion of excess Zn from the Zn1−xMgxO film into the CIGS interface is clearly observed in secondary ion mass spectroscopy (SIMS) depth profiles. These results indicate that excess Zn at the vicinity of the CIGS surface acts as non-radiative centers at the interface. The TRPL lifetime of the Zn1−xMgxO/CIGS film annealed at 250 °C reached values to be comparable to that of the as-deposited CdS/CIGS film. Performance of the Zn1−xMgxO/CIGS cells varied with the annealing temperature in the same manner as the TRPL lifetime. The highest efficiency of the Zn1−xMgxO/CIGS solar cells was achieved for annealing at 250 °C. The results of the TRPL lifetime on annealing show that the cell efficiency is strongly influenced by the Zn1−xMgxO/CIGS interface states related to the damages and diffusion of Zn. 相似文献
20.
A. Yamamoto M. Nakamura A. Seki E. L. Li A. Hashimoto S. Nakamura 《Solar Energy Materials & Solar Cells》2003,75(3-4):451-456
A simple spray method for the preparation of pyrite (FeS2) thin films has been studied using FeSO4 and (NH4)2Sx as precursors for Fe and S, respectively. Aqueous solutions of these precursors are sprayed alternately onto a substrate heated up to 120°C. Although Fe–S compounds including pyrite are formed on the substrate by the spraying, sulfurization of deposited films is needed to convert other phases such as FeS or marcasite into pyrite. A single-phase pyrite film is obtained after the sulfurization in a H2S atmosphere at around 500°C for 30 min. All pyrite films prepared show p-type conduction. They have a carrier concentration (p) in the range 1016–1020 cm−3 and a Hall mobility (μH) in the range 200–1 cm2/V s. The best electrical properties (p=7×1016 cm−3, μH=210 cm2/V s) for a pyrite film prepared here show the excellence of this method. The use of a lower concentration FeSO4 solution is found to enhance grain growth of pyrite crystals and also to improve electrical properties of pyrite films. 相似文献