Lithium electrochromism of atmospheric pressure plasma jet-synthesized NiO x C y thin films

Reversible lithium intercalation and deintercalation behavior of atmospheric pressure plasma jet (APPJ)-synthesized organonickel oxide (NiO _x C _y ) thin films under various substrate distances is testified in an electrolyte (1?M LiClO₄–propylene carbonate solution) at low driving voltages from ?0.5 to 1.5?V. Fast responses of 2?s bleaching at ?0.5?V and 6?s coloration at +1.5?V are accomplished for the nano-porous NiO _x C _y thin films. This study reveals that a rapid synthesis of electrochromic NiO _x C _y thin films in a single process via APPJ by 21?s is investigated. This study presents a noteworthy electrochromic performance in a light modulation with up to 43% of transmittance variation and a coloration efficiency of 36.3?cm²/C at a wavelength of 830?nm after 200?cycles of cyclic voltammetry measurements.     

Enhanced lithium electrochromic performance of tungsten oxide films by rapid co-synthesis of iron and tantalum oxides using cold atmospheric pressure plasma polymerization

Journal of Solid State Electrochemistry - Lithium electrochromic performance of organo-tungsten oxynitride (WOz1Cz2Nz3) films enhanced by additions of organo-iron oxynitride (FeOz1Cz2Nz3) or...     

Enhanced lithium ionic intercalation and conduction performance of flexible iron oxide films using an atmospheric pressure plasma jet

Journal of Solid State Electrochemistry - Enhancement on lithium ionic intercalation and conduction performance of flexible-organo-iron oxide (FeO y C z ) films, via a rapid co-synthesis with...     

Quantum chemical modeling of electrochromism of tungsten oxide films

A cluster model is proposed to describe the excitations in solid tungsten oxide. The density-functional theory approach is used to calculate the ground-state electronic structure of the model cluster and its optimum geometry; subsequently, time-dependent density-functional theory calculations are performed to obtain the oscillator strengths and energies of the excited states. The results are reported both for the electrically neutral cluster and for the cluster with an extra electron (mimicking the effect of electron injection from the cathode). They correctly locate the electrochemically active transition. The corresponding wave functions are delocalized, suggesting that electron localization at one tungsten center is rather unlikely, thereby shedding doubt as to the validity of the polaron model. Local lattice distortions presumably created at the stage of sample preparation are found to affect the excitation energies to a considerable extent, which explains the experimentally observable large width of optical absorption responsible for electrochromism.     

Enhanced lithium-ion intercalation and conduction of transparent tantalum oxide films by lithium addition with an atmospheric pressure plasma jet

An investigation is conducted on enhancing lithium-ion intercalation and conduction performance of transparent organo tantalum oxide (TaO _y C _z ) films, by addition of lithium via a fast co-synthesis onto 40 Ω/□ flexible polyethylene terephthalate/indium tin oxide substrates at the short exposed durations of 33–34 s, using an atmospheric pressure plasma jet (APPJ) at various mixed concentrations of tantalum ethoxide [Ta(OC₂H₅)₅] and lithium tert-butoxide [(CH₃)₃COLi] precursors. Transparent organo-lithiated tantalum oxide (Li _x TaO _y C _z ) films expose noteworthy Li⁺ ion intercalation and conduction performance for 200 cycles of reversible Li⁺ ion intercalation and deintercalation in a 1 M LiClO₄-propylene carbonate electrolyte, by switching measurements with a potential sweep from ?1.25 to 1.25 V at a scan rate of 50 mV/s and a potential step at ?1.25 and 1.25 V, even after being bent 360° around a 2.5-cm diameter rod for 1000 cycles. The Li⁺ ionic diffusion coefficient and conductivity of 6.2?×?10^?10 cm²/s and 6.0?×?10^?11 S/cm for TaO _y C _z films are greatly progressed of up to 9.6?×?10^?10 cm²/s and 7.8?×?10^?9 S/cm for Li _x TaO _y C _z films by co-synthesis with an APPJ.     

Fabricating polypyrrole/tungsten oxide hybrid based electrochromic devices using different ionic liquids

A facile approach of polypyrrole (PPy)/tungsten oxide (WO₃) composites electrosynthesized in ionic liquids for fabrication of electrochromic devices is discussed. The electrochromic properties of PPy/tungsten oxide nanocomposite films (PPy/WO₃) prepared in the presence of four different ionic liquids, 1‐butyl‐3‐methylimidazolium tetrafluoroborate (BMIMBF₄), 1‐butyl‐3‐methylimidazolium hexafluorophosphate (BMIMPF₆), 1‐butyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl) imide (BMIMTFSI), and 1‐butyl‐1‐methylpyrrolidinium bis(trifluoromethylsulfonyl) imide (BMPTFSI) were investigated in detail. Cyclic voltammetry results revealed that PPy/WO₃ nanocomposite films have much more electrochemical activity than those of WO₃ and PPy film. The electrochromic contrast, coloration efficiency, and switching speed of the composite films were determined for electrochromic characteristics. The maximum contrast and the maximum coloration efficiency values were measured as 33.25% and 227.89 cm²/C for the PPy/WO₃/BMIMTFSI composite film. Copyright © 2015 John Wiley & Sons, Ltd.     

Structure and optical properties of CVD molybdenum oxide films for electrochromic application

Vibrational and optical properties of MoO₃ thin films have been studied by Raman and infrared spectroscopy. The films were deposited onto Si substrates at a temperature of 150 °C by chemical vapor deposition of Mo(CO)₆ at atmospheric pressure and different amounts of oxygen in the reactor. The Raman and IR spectral analyses show that the as-deposited films are in general amorphous. Post-deposition annealing at 300 and 400 °C leads to crystallization and the MoO₃ film structure is a mixture of orthorhombic and monoclinic MoO₃ modifications. Transformation of the monoclinic crystallographic modification to a thoroughly orthorhombic layered structure is observed for films heated at temperatures above 400 °C. Electronic Publication     

Oxygen addition effects on electrochromic properties of PECVD-synthesized WO x C y films for flexible electrochromic devices

An investigation was conducted into the electrochromic properties of organotungsten oxide WO _x C _y films synthesized onto 60 Ω/□ flexible polyethylene terephthalate/indium tin oxide substrates using low temperature, plasma-enhanced chemical vapor deposition (PECVD) at varying oxygen concentrations. The PECVD-synthesized WO _x C _y films were proven to offer remarkable electrochromic performance. Cyclic voltammetry switching measurements revealed that only low driving voltages from −1 to 1 V are needed to provide reversible Li⁺ ion intercalation and de-intercalation in a 0.1 M LiClO₄–PC electrolyte. Light modulation with transmittance variation of up to 72.9% and coloration efficiency of 62.5 cm²/C at a wavelength of 650 nm was obtained.     

Model of electrochromic and related phenomena in tungsten oxide thin films

We have developed a model of electrochromic and related phenomena in tungsten oxide thin films based on the assumption that the constitution of such films is heterogeneous and built up of nanosized particles, pores and adsorbed substances (mainly water). It is discussed why a high-efficiency reversible blue colour is observed in amorphous tungsten oxide films (α-WO₃ films) as well as why such porous thin films with polycrystalline or amorphous constitution and with a variety of particle properties can be easily obtained by a physical vapour deposition process in a low-pressure atmosphere in the presence of water. A substrate temperature in the range 450–550 K corresponds to some plateau on the water desorption curves which divided physically adsorbed water from chemically adsorbed water. Two types of structural units based on tetrahedrally and octahedrally coordinated tungsten ions have the main role in the formation of the film constitution. The tetrahedral structural units have a glass-forming function, but the octahedral ones have a modification function. From the electrochemistry point of view, the internal multiphase interfaces in such films are distributed multiphase electrodes. The adsorbed water together with defects of the oxide particles provide reagents for reversible coloration reactions in the film. The colour centres can be induced thermally (oxygen nonstoichiometry) or electrically (injected ions) or by radiation (photoinjected hydrogen). The electrochromism and related phenomenon of α-WO₃ films can be directly related to ion insertion/extraction processes controlled by external forces. Electronic Publication     

Kinetics of coloration of electrochromic tungsten oxide films produced by cathodic electrodeposition

The dependence of the kinetic characteristics of electrochromic indicator devices based on films of amorphous tungsten oxide α-WO₃ on the speed of reversible coloration of their working electrode with a film of this kind was studied.     

Optical,structural and electrochromic studies of molybdenum oxide thin films with nanorod structure

The MoO₃ thin films were prepared via sol–gel dip coating method on glass and FTO glass substrate. The optical and other properties of multilayered MoO₃ films with 2–10 layers were investigated. The MoO₃ films were studied using UV–Visible transmission, XRD, SEM, FTIR and Cyclic Voltammetry (CV) measurements. The band gap value for MoO₃ films was evaluated and in the range of 3.2 eV–3.72 eV. The XRD spectrum reveals that the crystallinity increases along the (020) and (040) planes with the increase in thickness. The SEM images showed the formation of nanorods upto six layers. The FTIR spectrum confirms the formation of MoO₃. The 6 layered films show the maximum anodic (spike)/cathodic (peak) diffusion coefficient of 18.84/1.701 × 10^?11 cm²/s. The same film exhibits the change in optical transmission of 49% with the bleached/coloured state transmission of 62/13%.     

A practical approach for generation of WO3-based flexible electrochromic devices

Journal of Solid State Electrochemistry - We managed to provide one-step facile electrochromic device (ECD) preparation to incorporate two cathodic coloring components into lithium ion (Li+)-doped...     

Lithium intercalation and conduction in Fe-containing tantalum oxide films synthesized with an atmospheric pressure plasma jet

Journal of Solid State Electrochemistry - Lithium ionic intercalation and conduction performance of tantalum oxides films improved by adding with iron oxides using an atmospheric pressure plasma...     

Polymer gel films with simple organic electrochromics for single-film electrochromic devices

Polymer gel films [poly(1-vinyl-2-pyrrolidinone-co-N,N′-methylenebisacrylamide) (PVPD)] which contain simple organic electrochromics [p-diacetylbenzene (p-DAB), dimethyl- or diethyl terephthalate (p-DMP or p-DEP)] are prepared and their optical responses to applied voltage are investigated. p-DAP/PVPD film is colored in green by the application of 1.2 V vs. Pt wire (quasireference electrode) across the film, and p-DMP/PVPD and p-DEP/PVPD films are colored in red by the application of ?2.5 and ?1.5 V vs. Pt, respectively. Their coloring responses are about a few seconds and the bleaching process also occurs rapidly. The films have no optical memory effect. © 1992 John Wiley & Sons, Inc.     

整体式三氧化钨/氧化石墨烯气凝胶增强可见光光催化氧化NO性能（英文）

近年来,光催化技术在去除以NO为代表的诸多室内气体污染物方面展现出巨大的潜力.单质铋和铋系氧化物,非金属氧化物以及钙钛矿等众多半导体光催化材料均具有优异的NO降解效率,但很难控制氧化产物.因而会生成大量毒性更强的中间产物NO2造成二次污染.因此,寻求一种清洁、高效,且具有良好选择性的光催化材料成为了亟待解决的问题.六方相三氧化钨(h-WO_3)的价带位置较正,氧化电位较高,具有很强的氧化能力,是一种良好的氧化性光催化半导体材料.然而,WO_3催化材料多为粉末状,不仅容易团聚,难以回收利用并且会堵塞检测气路.同时,WO_3本身存在的电子-空穴复合率高,弱的可见光响应性等问题使其光催化活性较低.因而,制备具有良好可见光响应,高电子-空穴分离效率的一体化WO_3材料是其广泛应用前急需解决的问题.而石墨烯气凝胶是理想的催化剂载体,其较高的比表面积以及多孔状结构可有效地增加催化剂的暴露面积,提升催化剂利用率;更重要的是,氧化石墨烯(GO)具有极高的导电率,可作为电子受体加速电子-空穴对的分离而提升光催化活性.因此,以GO作为基体材料,构建WO_3/GO气凝胶一体化材料有良好的应用前景.然而,现在还鲜见有关宏观WO_3/GO气凝胶光催化降解NO的报道.本文以偏钨酸铵为钨源,利用体积分数为25%的冰醋酸在180ⅹC条件下制备六方相三氧化钨.通过机械搅拌以及冷冻干燥法制备WO_3/GO气凝胶.经光催化氧化NO测试发现其可见光下降解率可达51%,是WO_3粉体的3.3倍,并且NO_2生成率仅为0.5%,远远低于其他相关光催化材料.采用了X射线衍射(XRD),透射电镜(TEM),X射线光电子能谱(XPS),紫外-漫反射分光光度计(UV-DRS),傅里叶红外光谱(FTIR)和荧光光谱(PL)等手段研究了其光催化性能提高的原因.XRD测试显示,复合材料主体为h-WO_3,说明GO的引入并未破坏材料晶体结构;TEM和BET测试发现,在加入GO之后h-WO_3分散性变好,比表面积变大,从而可暴露更多的光催化活性位点.UV-DRS吸收光谱可以看到WO_3/GO气凝胶材料的吸收边发生了显著的红移,其禁带宽度从3.44 eV减小到3.16 eV,这可能是GO影响了WO_3的能带结构所致.同时PL结果表明,引入了GO之后,气凝胶材料的非辐射跃迁程度明显减小表明其电子-空穴对的复合得到了显著抑制,电子迁移显著加强.综合以上结果,可以得到WO_3/GO光催化性能提升以及良好的产物选择性的原因.首先,三维气凝胶材料的结构提升了催化剂的有效利用率,较大的比表面积暴露了更多的活性位点.其次,GO的引入减小了复合材料的禁带宽度,并使其吸光性能有所改善,产生了更多的光生电子和空穴.最后,GO本身极高的导电性,使光生电子-空穴对得以有效的分离,一方面,电子通过GO迅速转移到材料表面来参与光催化反应;另一方面,电子的快速转移抑制了电子-空穴对的复合,进而提高光催化性能,而且较正的价带位置保证了NO较为彻底的氧化为NO3–.因此,相比传统粉末WO_3催化材料,一体化的WO_3/GO气凝胶不仅显著提升了NO降解率,同时严格抑制了毒副产物NO2的生成,同时更具有容易回收利用,不存在二次污染的优点.综上所述,WO_3/GO一体化气凝胶光催化材料有望在环境净化与能源领域表现出良好的应用前景.     

Ultra fast electrochromic switching of nanoporous tungsten-tantalum oxide films

Self-organized nanoporous oxide layers were grown on a W-Ta alloy by electrochemical anodization. These nanostructured mixed oxide layers show an ultra-fast electrochromic switching kinetics. Compared with porous WO(3) nanostructures more than 10 times higher switching frequencies are reached along with a significantly enhanced lifetime and cyclability.     

Deposition of thin films and coatings by atmospheric pressure vapor plasma jet

An atmospheric pressure plasma jet generated by inductively coupled RF discharge and containing vapors of silicon compounds in argon-carrier gas was used to deposit a-Si∶H, a-Si∶(H, O), and a-SiC film. Rapid deposition up to 10 μm/min results from efficient material transport and is limited mainly by rates of surface reactions. Morphology, structure, and composition of deposits were studied.     

Mixed micellar medium for the spectrophotometric determination of molybdenum in molybdenum/tungsten mixtures

Effects of cetyltrimethylammonium bromide (CTAB) and/or nonylphenoxypolyethoxyethanol (OP) on the absorption spectra of the complexes of molybdenum and tungsten with bromopyrogallol red (BPR) were studied. Based on these effects, a mixture of CTAB and OP was thus selected as a medium for the selective and sensitive determination of Mo in Mo/W binary mixtures. Under the optimum conditions, Beer's law was obeyed over the range 0.06-0.8 mug ml(-1) Mo with molar absorptivity being 1.3x10(5) l mol(-1) cm(-1) and detection limit 0.025 mug ml(-1). For 1.0 mug Mo, at least 20 mug W did not interfere in the determination of Mo with average recovery and relative standard deviation being 99.5% and <2%, respectively. The method developed maintained the features of simplicity and rapidity and, moreover, its selectivity and sensitivity enhanced greatly due to the use of CTAB/OP mixed micellar medium. When coupled with a compatible concentration method, the proposed method could be used for the determination of trace Mo in natural waters.