Nanostructured NiO based all solid state electrochromic device

A nickel oxide film with a thickness of 445 nm was deposited from nickel acetate precursor using the sol–gel dip coating method. The NiO films exhibit optical transmission of 84% at 550 nm and direct energy gap (E _gd) value is 3.64 eV. The FTIR spectrum of the films confirms the formation of Ni–O bond. XRD spectrum reveals the formation of nano crystallites along (111) and (200) planes with a particle size of 17 nm. The electrochromic properties have been studied using cyclic voltammetric (CV) technique. The optical transmission of a glass/FTO/NiO/ZrO₂/FTO/glass EC device is reported.     

Dependence of NO<Subscript>2</Subscript> sensitivity on thickness of oxide-sensing electrodes for mixed-potential-type sensor using stabilized zirconia

The effect of thickness of oxide-sensing electrode (SE) on NO₂ sensitivity of the planar sensor based on yttria-stabilized zirconia (YSZ) was examined at high temperatures. The sensitivity of the sensor increased with decreasing thickness of SE, and the highest sensitivity was obtained by using the thinnest layer of Cr₂O₃–SE (2.7 μm) at 700 °C. In the case of NiO–SE, the highest sensitivity was observed for the sensor using the 4 μm-thick SE even at high temperature of 850 °C. Based on the results of the measurements for the complex impedances, the polarization curves, and the gas-phase NO₂ decomposition catalysis, it was confirmed that the catalytic activity to the gas-phase NO₂ decomposition on the oxide–SE matrix played an important role in determining the NO₂ sensitivity of the present sensors. This artice was accidentally published twice. This is the second publication, please cite only the authoritative first one which is available at . An additional erratum is available at . An erratum to this article can be found at     

镍基气凝胶催化CH_4-CO_2重整制取合成气反应的研究 Ⅰ.制备方法对NiO-CeO_2-Al_2O_3催化剂物化性质的影响

采用浸渍法、溶胶 凝胶过程与普通干燥、超临界干燥过程相结合的方法制备了具有不同结构特点的NiO CeO2 Al2 O3催化剂 ,分别为浸渍型催化剂 (iNCA)、干凝胶催化剂 (xNCA)和气凝胶催化剂 (aNCA) ,利用BET、TEM、XRD、TPR、NH3 TPD、H2 TPD等方法对各催化剂样品的物化性质进行了考察。研究结果表明 ,经 82 3K焙烧后 ,镍含量为 9%的各催化剂样品中镍物种均分散良好 ;与iNCA相比 ,以溶胶 凝胶法为基础制备的xNCA和aNCA中镍物种与载体的相互作用强并且存在状态均一 ;三种催化剂中 ,气凝胶样品具有比表面积高、堆密度低、表面酸中心数多及表面镍分散度高的特点。     

纳米氧化镍的固相合成

纳米氧化镍的固相合成;NiO;纳米粒子;固相反应;合成机理     

High‐performance gas‐sensing properties of octahedral NiO crystals prepared via one‐step controllable synthesis route

Octahedrally shaped NiO powders have been synthesized via a one‐step composite‐hydroxide‐mediated method without any surfactant. The synthesized materials are characterized by XRD, EDS, TEM and FESEM techniques. Each particle exhibited a nearly perfect octahedron shape with sharp edges and corners as well as smooth surfaces. The octahedral NiO particles performed better gas‐sensitivity toward ethanol than that of NiO nanopowders, which was attributed to the exposed ｛111｝ facets of octahedron. The result was confirmed by the first‐principle calculation which indicated that the (111) facet was more active than (100) and (110) facet.     

Optical and electrochemical properties of Cu-doped NiO films prepared by electrochemical deposition

Cu-doped nickel oxide (NiO) thin films were prepared by electrochemial deposition (cathodic deposition) technique onto the fluorine doped tin oxide (F: SnO₂; FTO) coated glass substrates from organic solutions. Effects of Cu content on the morphology, structure, optical and electrochromic properties of NiO films were investigated by means of scanning electron microscope (SEM), X-ray diffraction (XRD), ultraviolet-visible spectrophotometer (UV-vis) and cyclic voltammetry (CV), respectively. SEM images indicated the formation of nanorods after Cu was added. The films were formed with amorphous or short-range ordered NiO grains and a trace of face-centered cubic Ni_xCu_1−xO confirmed by XRD. The transmittances of both bleached state and colored state were significantly lowered when Cu was added. The NiO films doped with Cu (the molar ratio was 1/8) exhibited the optimum electrochromic behavior with a variation of transmittance (ΔT) up to ∼80% at the wavelength range of 350-600 nm. Cu doping reduces the response time for both the coloring and bleaching states, and the reversibility of the redox reaction was increased as well.     

Nanoporous nickel oxide thin films and its improved electrochromic performance: Effect of thickness

Electrochromic properties of chemically bath deposited nanoporous NiO thin films were investigated as a function of film thickness using Ni sulphate precursor, aqueous ammonia and potassium persulphate as complexing and oxidizing agents respectively. The films were characterized for their structural, morphological, optical and electrochromic properties using X-ray diffraction, scanning electron microscopy, FT-IR spectroscopy, cyclic voltammetry, chronoamperometry and optical transmittance studies. X-ray diffraction patterns show that the films are polycrystalline, consisting of NiO cubic phase. Infrared spectroscopy results show the presence of free hydroxyl ion and water in NiO thin films. SEM micrographs revealed nanoporous nature composed of interconnected nanoporous network, forming well defined 3D nano envelopes. The optical band gap energy was found to be decreased from 3.22 to 2.80 eV with increasing film thickness. The electrochromic properties of all the films were investigated in aqueous (KOH) and non aqueous (LiClO₄-PC) electrolyte by means of cyclic voltammetry (CV), chronocoulometry (CC) and optical studies. The transmittance modulations or optical density differences during the coloring/bleaching process were found to be increased with the film thickness. This increment in optical differences led to an increase in coloration efficiency (CE) to about 95 cm²/C, which is two times more than that observed in KOH and response time of 2.9 s for bleaching (reduction) and 3.5 s for coloration (oxidation) observed for the film deposited at 60 min with excellent electrochemical stability up to 3000 c/b cycles in LiClO₄-PC electrolyte.     

Sol-gel based alumina powders with catalytic applications

The sol-gel process provides a new approach to the preparation of oxide materials and offers many advantages for making catalysts. Since homogeneous mixing can be achieved at the molecular scale, the chemical reactivity of the oxide surface can be greatly enhanced; thus powders with high surface area and optimized pore size distribution can be obtained at low temperatures. In the present work NiO/Al₂O₃ sol-gel catalysts were obtained by simultaneous gelation of aluminium isopropoxide and nickel nitrate. A comparative study with pure sol-gel alumina was also realized. By physical-structural studies the changes induced by the introduction of the Ni precursor, before and after aluminium alkoxide hydrolysis were highlighted. The introduction of Ni at the beginning of the reaction favors γ-Al₂O₃ crystallization. When Ni is added at the end of reaction, it delays the alumina crystallization and induces the disorder of the lattice. The obtained Ni doped sol-gel derived alumina has been used as catalyst in the finished form for glycerol reforming to generate H₂ for fuel cell applications. Some evaluation results of Ni-doped alumina combined with TiO₂ in photocatalytic glycerol reforming reaction have been included.     

Graphene oxide decorated bimetal (MnNi) oxide nanoflakes used as an electrocatalyst for enhanced oxygen evolution reaction in alkaline media

Precious non-noble metals have been constantly attracting research attention in order to realize an inexpensive, extra active and more stable electrocatalysts in terms of various oxidation states and structures for their applications in oxidation (splitting) of water. In the present work graphene oxide incorporated, MnO₂-NiO composite metal oxide nanoflakes were synthesized on the stainless steel substrate using efficient electrodeposition route in alkaline media and drop casting method with further annealing treatment at 400 °C for 4 h. Initially MnO₂-NiO nanoflakes were deposited using different cyclic sweep rates, later graphene oxide suspension was drop casted on the MnO₂-NiO nanoflakes and subsequently subjected to annealing at 200 °C for 2 h. The prepared electrode material is denoted as GO/MnO₂-NiO/SS and used as an electrocatalyst for oxygen evolution. Field emission scanning electron microscopy, transmission electron microscopy, Energy dispersive electron spectroscopy and X-ray diffraction spectroscopy were used to study the crystalline nature and morphologies of the deposited films. The electrochemical properties of the electrode material were investigated using cyclic voltammetry and linear sweep voltammetry. The electrode exhibits low overpotential and small Tafel slope of 379 mV and 47.84 mVdec⁻¹ at the current density of 10 mA cm⁻² in alkaline (KOH) medium. In addition, the electrode shows a long time stability of 28800 s. Hence, the present study suggests that the GO incorporated Mn-Ni bimetal oxide modified electrode is suitable electrode material for oxygen evolution reaction (OER), owing to its facile preparation, inexpensive, easy handling and high active nature.