Microwave assisted novel MoBi2S5 nanoflowers: Synthesis,characterization, photoelectrochemical performance

In the present article, we have studied the effect of post annealing treatment on microstructural, optical and photoelectrochemical (PEC) properties of MoBi₂S₅ thin films synthesized by microwave assisted technique. The synthesized thin films are vacuum annealed for 4 h at 473 K temperature. The X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM) and UV–Vis–NIR spectrophotometer techniques were used for characterization of the as deposited and annealed MoBi₂S₅ thin films. The XRD patterns confirm the synthesized and annealed thin films have nanocrystalline nature with rhombohedral-orthorhombic crystal structure. SEM micrographs indicate that, nanoflowers exhibit sharper end after annealing. The optical absorption study illustrates that the optical band gap energy has been decrease from 2.0 eV to 1.75 eV with annealing. Finally, applicability of synthesized thin films has been checked for PEC property. The J-V curves revealed that synthesized thin film photoanodes are suitable for PEC cell application. As well, used simple, economical method has great potential for synthesis of various thin film materials.     

X-Ray Analysis of Multi-Films for Electrochromic Device Application

Multilayer films based on tungsten oxide (WO₃), ITO (indium tin oxide) and CdS were deposited mainly by reactive dc magnetron sputtering onto glass substrates for electrochromic application. The thin films were analyzed by means of XPS (X-ray photoelectron spectroscopy), GIXD (grazing incidence X-ray diffraction) and XRD (X-ray diffraction). XRD and XPS results confirmed that the films were WO₃, CdS and ITO, respectively. The surface and interface of the CdS/ITO bi-layered film was studied by GIXD in different incidence angles. Detailed results about the amorphous characterization of the films during room temperature growth and post annealing are given.     

Improving the contact properties of CdS-decorated TiO<Subscript>2</Subscript> nanotube arrays using an electrochemical/thermal/chemical approach

Decoration of TiO₂ nanotube films (TiO₂ nanotube arrays (TNAs)) with CdS nanoparticles has been pursued for a broad range of applications that goes from solar cells to biological sensors. In most synthesis methods, the scale-up of devices has been challenging due to the poor contact at the chalcogenide/oxide interface. In this work, we validate the electrochemical/thermal/chemical route as a superior strategy to sensitize TNAs with CdS nanoparticles when compared with conventional methods. The process consisted of (i) electrodeposition of cadmium on TNAs to ensure strong bonding between TiO₂ and Cd precursor particles, (ii) air annealing of Cd-decorated TNAs to thermally oxidize cadmium to cadmium oxide, and (iii) total sulfurization of cadmium oxide to obtain CdS in an hexagonal phase matching that of TNAs. X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) analyses indicated the complete transformation of cadmium precursor particles into CdS and a good surface coverage of the internal/external walls of TNAs. When compared to samples prepared by successive ionic layer adsorption and reaction (SILAR), electrochemical impedance spectroscopy data revealed the improvement of the electrical properties of the TNA matrix due to the sulfurization process and a lower contact resistance at the CdS/TNA interface. These improvements explain the superior photoelectrochemical response of CdS/TNA photoelectrodes obtained by the electrochemical/thermal/chemical route.     

Ion-exchange synthesis and improved photovoltaic performance of CdS/Ag2S heterostructures for inorganic-organic hybrid solar cells

A facile ultrasound-assisted ion exchange route was developed for the synthesis of CdS/Ag₂S heterojunctions by ion exchange between the nanostructured CdS film and [Ag(NH₃)₂]⁺ under ultrasonication. The CdS/Ag₂S heterojunction film was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-vis DRS spectroscopy, photoelectrochemical measurements, and the transient photovoltage (TPV) technique. CdSAg₂S heterojunctions exhibit a dense morphology, enhanced visible light absorption and stronger photocurrent response than the pure CdS films. Poly(3-hexylthiophene) (P3HT) was then spin coated into the CdS/Ag₂S framework. Hybrid solar cells constructed with FTO/CdS/Ag₂S/P3HT/Au display relatively higher power conversion efficiency than FTO/CdS/P3HT/Au.     

电沉积-退火工艺制备铜铟硒太阳能电池薄膜及表征

CuInSe₂ (CIS) films with good crystalline quality were synthesized by electrodeposition followed by annealing in Se vapor at 530 oC. The morphology, composition, crystal structure, optical and electrical properties of the CIS films were investigated by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, Raman spectroscopy, UV-VIS-NIR spectroscopy, and admittance spectroscopy. The results revealed that the annealed CIS films had chalcopyrite structure and consisted of relatively large grains in the range of 500-1000 nm and single grain of films extend usually through the whole film thickness. The band gap of CIS films was 0.98 eV and carrier concentration was in the order of 10¹⁶ cm^-3 after etching the Cu-Se compounds on the film surface. Solar cells with the structure of AZO/i-ZnO/CdS/CIS/Mo/glass were fabricated. Current density vs. voltage test under standard reported condition showed the solar cells with an area of 0.2 cm² had a conversion efficiency of 0.96%. The underlying physics was also discussed.     

Microstructural and chemical transformation of thin Ti/Pd and TiD<Subscript><Emphasis Type="BoldItalic">y</Emphasis></Subscript>/Pd bilayer films induced by vacuum annealing

Using a combination of scanning electron microscopy, transmission electron microscopy (TEM), X-ray diffraction and X-ray photoelectron spectroscopy (XPS), we made a comparative study of the high-temperature annealing impact on thin titanium deuteride (TiD _y ) films covered by an ultrathin Pd layer, and on Ti/Pd bilayer films. The bilayer films were prepared under ultrahigh vacuum conditions and were in situ annealed using the same annealing procedure. It was found that the surface and the bulk morphology of both films undergo different annealing-induced transformations, leading to an extensive intermixing between the Ti and Pd layers and the formation of a new PdTi₂ bimetallic phase. Energy-filtered TEM imaging and energy-dispersive X-ray spectrometry analysis, as well as XPS depth profiling all provided evidence of a different distribution of Pd and Ti in the annealed TiD _y /Pd film compared with the annealed Ti/Pd film. Our results show that thermal decomposition of TiD _y , as a consequence of annealing the TiD _y /Pd film, modifies the intermixing process, thereby promoting Ti diffusion into the Pd-rich top layer of the TiD _y film and thus providing a more likely path for the formation of the PdTi₂ phase than in an annealed Ti/Pd film. Figure Figure Microstructural and chemical characterisation of thin TiDy/Pd film after annealing     

CuInS2：两步电沉积制备及性能

采用恒电位沉积法制备铜铟合金预制膜,并存管式炉中通过固态源蒸发硫化预制膜得到CuInS:薄膜.通过扫描电镜(SEM)、能量色散谱仪(EDS)和X射线衍射仪(XRD)对CuInS2薄膜的表而形貌、截面厚度、成分组成和薄膜的组织结构进行了研究,并利用紫外可见光吸收谱仪(UV-Vis)研究了不同硫化温度对CuInS:薄膜的形貌及其光学吸收性质的影响.结果表明:不同的退火温度能够影响CuInS:薄膜的表面形貌以及带隙的大小,从而影响其光学吸收特性.     

The effects of oxygen concentration on ultraviolet luminescence of ZnO films by sol–gel technology and annealing

ZnO thin films were successfully deposited on SiO₂/Si substrate using the sol–gel technique and annealed in various annealing atmospheres at 900 °C by rapid thermal annealing (RTA). X-ray diffraction revealed the (002) texture of ZnO thin films. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed that the grains of the ZnO thin film were enlarged and its surface was smoothed upon annealing in oxygen. PL measurement revealed two ultraviolet (UV) luminescence bands at 375 and 380 nm. The intensity of the emission peak at 380 nm became stronger as the concentration of oxygen in the annealing atmosphere increased. The X-ray photoelectron spectrum (XPS) demonstrated that a more stoichiometric ZnO thin film was obtained upon annealing in oxygen and more excitons were generated from the radiative recombination carriers consistently. Additionally, the UV intensity increased with the thickness of ZnO thin film.     

Li doped and undoped ZnO nanocrystalline thin films: a comparative study of structural and optical properties

Thin films of ZnO were grown by the sol–gel method using spin-coating technique on (0001) sapphire substrates. The effect of doping after annealing on the structural and optical properties has been investigated by means of X-ray diffraction (XRD), cathodoluminescence (CL) spectrum, scanning electron microscopy (SEM) and atomic force microscopy (AFM). The films that were dried at 623 K and then post annealed at 873 K showed (0002) as the predominant orientation. Two emission bands have been observed from CL spectrum. Lithium doped film shows shift in the near band edge UltraViolet emission peak and suppressed defect level emission peak in the visible range. SEM analysis of the films exhibits many spherical shaped nanoparticles. Roughness of the films determined using atomic force microscopy.      

Preparation of Titanium Oxide Layer on Silica Glass Substrate with Titanium Naphthenate Precursor

Nanocrystalline TiO₂ thin films on silica glass substrates were prepared by using a naphthenic acid precursor. As-deposited thin films were heat treated at 500, 600, 700 and 800^∘C for 30 min in air. The TiO₂ thin films were analyzed by High Resolution X-ray diffraction, ultra violet—visible—near infrared spectrophotometer, field emission—scanning electron microscope and scanning probe microscope. After annealing at 600 and 700^∘C, the XRD patterns consist of only anatase peaks of TiO₂ film. Rutile(110) peak begins to appear at an annealing temperature of 800^∘C. Relative high transmittance at visible range was obtained for all films except the film annealed at 800^∘C. Optical band gap, E_g, is in the range between 3.53 and 3.78 eV except the TiO₂ film annealed at 500^∘C. The best hydrophilicity was achieved with a high-temperature annealing.     

P3HT修饰一维有序壳核式CdS/ZnO纳米棒阵列复合膜的光电化学性能

采用电化学方法在铟锡氧化物(ITO)导电玻璃上制备了高度有序的ZnO纳米棒阵列, 在ZnO纳米棒阵列上先后电化学沉积CdS纳米晶膜及聚3-己基噻吩(P3HT)薄膜得到P3HT修饰的一维有序壳核式CdS/ZnO纳米阵列结构, 并通过扫描电镜(SEM)、透射电镜(TEM)、X射线衍射(XRD)、能量散射X射线(EDX)等表征手段证实了该结构的形成. 以此纳米结构薄膜为光阳极组装新型半导体敏化太阳电池, 研究了CdS纳米晶膜的厚度和P3HT薄膜的沉积对电池光伏性能的影响, 初步探讨了电荷在电池结构中的传输机理, 结果表明, CdS纳米晶膜和P3HT薄膜的沉积有效地拓宽了光阳极的光吸收范围, 实验中电池的光电转换效率最高达到1.08%.     

Formation of Rod-Like CuInS2 Nanocrystals on the Glass Substrate

Rod-like CuInS₂ nanocrystals on the glass substrate were prepared by annealing the coat of CuInS₂ nanoparticles. The products were characterized by means of energy dispersive analysis of x-ray (EDAX), x-ray diffraction (XRD) and scanning electron microscopy (SEM). The results of XRD and EDAX show that the rod-like CuInS₂ nanocrystals obtained are of a chalcopyrite structure and are nearly stoichiometric. The aggregation mechanism of “oriented attachment” of nanocrystals is believed to be operative and compatible in this study.     

CdS/FTO thin film electrodes deposited by chemical bath deposition and by electrochemical deposition: A comparative assessment of photo-electrochemical characteristics

CdS thin films have been deposited onto FTO/glass substrates by two different techniques, electrochemical deposition (ECD) and chemical bath deposition (CBD). Feasibility of using these two film types in photoelectrochemical processes has been critically investigated here. The films were comparatively characterized by a number of techniques (solid state absorption spectra, solid state photoluminescence spectra, XRD and SEM). PEC characteristics of the electrodes, including current density–voltage (J–V) plots, conversion efficiency (η), stability and fill-factor (FF) were then studied. The results show that both systems involved nano-sized CdS particles living in coagulates. The ECD was thinner and more uniform than the CBD system. The CBD films were more effective in PEC processes than the ECD counterparts. Effect of annealing on characteristics of both electrode systems has been investigated. Annealing enhanced both film characteristics, but the CBD was affected to a higher extent, and the annealed CBD film was more effective than the ECD counterpart.     

Formation of cadmium sulfide (CdS) nanofilm on a Cd(OH)2/SiO2 precursor layer

Dense thin nanostructured films of cadmium sulfide CdS obtained by chemical deposition from aqueous solutions are strongly bound to a substrate due to the formation of cadmium hydroxide Cd(OH)₂ in the system. By X-ray reflectometry and grazing incidence diffraction it is found that at the beginning of the deposition a dense Cd(OH)₂/SiO₂ layer is produced on the surface of a silicon or glass substrate. This layer is formed through the atomic-layer adsorption of crystalline 1–3 nm thick Cd(OH)₂ film by the oxygencontaining substrate surface. During sulfidation of this cadmium-containing substrate layer, a surface nucleation layer of CdS/Cd(OH)₂/SiO₂ forms, which provides the growth, denseness, and strong adhesion to the substrate of nanostructured CdS film with a disordered structure. According to the obtained experimental data, a “hydroxide scheme” of film deposition is confirmed and refined, and the stages of CdS nanofilm formation are determined.     

Synthesis of CuInS2@CdS Core‐Shell Nanocrystals

CuInS₂@CdS core‐shell nanocrystals were prepared in a wet chemical process. Transmission electron microscope (TEM), x‐ray energy dispersive spectroscopy (EDAX), x‐ray diffraction (XRD), absorption, and photoluminescence (PL) spectra were used to confirm the formation of the CuInS₂@CdS core‐shell structure. The growth of CdS shell not only increased the PL intensity, but also restrained the transformation of CuInS₂ from nanoparticles to nanorods after annealing, which was attributed to an effective chemical passivation of the CuInS₂ core by the CdS shell.     

Effect of sol temperature on the structure,morphology, optical and photoluminescence properties of nanocrystalline zirconia thin films

Transparent nanocrystalline zirconia thin films were prepared by sol–gel dip coating technique using Zirconium oxychloride octahydrate as source material on quartz substrates, keeping the sol at room temperature (SET I) and 60 °C (SET II). X-ray diffraction (XRD) pattern shows the formation of mixed phase [tetragonal (T) + monoclinic (M)] in SET I and a pure tetragonal phase in SET II ZrO₂ thin films annealed at 400 °C. Phase transformation from tetragonal to monoclinic was achieved in SET II film annealed at 500 °C. Atomic force microscopy analysis reveals lower rms roughness and skewness in SET II film annealed at 500 °C indicating better optical quality. The transmittance spectra gives a higher average transmittance >85% (UV–VIS region) in SET II films. Optical spectra indicate that the ZrO₂ films contain direct—band transitions. The sub- band in the monoclinic ZrO₂ films introduced interstitial O⁻defect states above the top of the valance band. The energy bandgap increased (5.57–5.74 eV) in SET I films and decreased (5.74–5.62 eV) in SET II films, with annealing temperature. This is associated with the variations in grain sizes. Photoluminescence (PL) spectra give intense band at 384 and 396 nm in SET I and SET II films, respectively. A twofold increase in the PL intensity is observed in SET II film. The “Red” shift of SET I films and “Blue” shift of SET II films with annealing temperature, originates from the change of stress of the film due to lattice distortions.     

溶胶浸渍模板法制备有序多孔氧化钛、氧化锌薄膜

采用溶胶浸渍模板法制备了有序多孔的氧化钛(TiO₂)和氧化锌(ZnO)薄膜。首先，在洁净的玻璃基片上通过浸渍-提拉工艺组装有序的聚苯乙烯微球(PS)阵列模板；然后再采用溶胶浸渍法将TiO₂和ZnO溶胶灌充到PS模板微球的间隙内；最后通过煅烧去除PS而得多孔薄膜。采用SEM观察了薄膜的表面形貌，并用XRD对薄膜的性能进行了表征。结果表明，溶胶的浓度对薄膜形貌有着显著的影响。经煅烧后，TiO₂和ZnO薄膜分别为锐钛矿和六方纤锌矿结构。此外，对模板的组装及溶胶的灌注过程进行了分析。     

Effect of thermal annealing on the crystalline structure of PVDF/PMMA-modified graphene nanocomposites

Abstract

Poly(vinylidene fluoride)-based nanocomposite films with different loadings of PMMA-modified graphene sheets were prepared by a solution-mixing and solvent casting method. The prepared films were annealed at three different temperatures and the crystalline structures of the samples were investigated. X-ray diffraction data confirmed the PMMA-modified graphene nanosheets enhanced the preferential β-crystalline structure when increasing the annealing temperature to 90?°C, while increasing the annealing temperature to 120?°C led to a β → γ phase conversion. The tendency of the graphene sheets to restack by increasing the annealing temperature was confirmed by XRD. The PMMA-modified graphene sheets, however, didn’t showa nucleating effect on the PVDF crystallizationduring DSC cooling scans.     

Enhanced photo-catalytic activity of TiO2 nanostructured thin films under solar light by Sn and Nb co-doping

In this study, preparation of Sn and Nb co-doped TiO₂ dip-coated thin films on glazed porcelain substrates via sol–gel process have been investigated. The effects of co-doping content on the structural, optical, and photo-catalytic properties of applied thin films have been studied by X-ray diffraction (XRD), field emission SEM (FE-SEM), high resolution transmission electron microscopy (HR-TEM), and UV–Vis absorption spectroscopy. Surface chemical state of thin films was examined by atomic X-ray photoelectron spectroscopy (XPS). XRD results suggest that adding impurities has a great effect on the crystallinity and particle size of TiO₂. Titania Rutile phase formation in thin film was promoted by Sn⁴⁺ addition but was inhibited by Nb⁵⁺ doping. The prepared co-doped TiO₂ photo-catalyst films showed optical absorption edge in the visible light area and exhibited excellent photo-catalytic ability for degradation of methylene blue (MB) solution under solar irradiation. Comparison with undoped and Sn or Nb-doped TiO₂, codoped TiO₂ shows an obviously higher catalytic activity under solar irradiation.     

纳米晶状磷酸钙盐/Al2O3-Ti生物复合材料的制备与结构表征

0引言众所周知,钛及其合金具有优良的机械力学性能,但其生物活性不足。因此,在金属基体上涂敷一层生物活性涂层,结合金属与生物活性材料的各自优势,已成为世界各国学者研究最为活跃的生物复合材料体系之一。该体系可用于临床医学,作为人体硬组织等的修复替换材料。目前,已开发出多种在金属基体上制备生物活性涂层的工艺和方法。如:等离子沉积法[1]、离子束溅射法[2]、激光熔覆法[3]、溶胶鄄凝胶法[4]、电化学沉积与水热处理合成法[5]、电泳沉积[6]、电结晶[7]等多种方法。但现有涂层材料尚存在一些问题:(1)由于替换材料的高硬度而导致其周围硬组织坏死[8];(2)由于疲劳磨损或热膨胀不匹配引起涂层脱落[9];(3)由于异质相导致生物活性降解[10]。因此,研究新的制备工艺,开发新的生物复合材料体系就显得十分重要。考虑到Al2O3具有优异的抗磨损、耐腐蚀等性能,以及较好的生物相容性,常作为临床选用的人造硬组织承载材料[11],故在本研究工作中,我们首次采用阳极氧化与水热处理复合工艺研制酸式磷酸钙/Al2O3鄄Ti生物复合材料体系。该体系不同于由日本Ishizawa等研制的HAp/TiO2鄄Ti复合体系[12]。主要体现在两...