Improved electrochromic performance of hierarchically porous Co3O4 array film through self-assembled colloidal crystal template

A hierarchically porous cobalt oxide (Co₃O₄) array film, in which the skeleton is composed of ordered non-close-packed bowl array possessing nanoporous walls, is successfully prepared by electrodeposition through self-assembled monolayer polystyrene sphere template. As an anodic coloring material for electrochromic application, the hierarchically porous Co₃O₄ array film exhibits enhanced electrochromic properties with higher optical modulation, faster switching speed and better cycling performance, compared to dense Co₃O₄ film. The porous Co₃O₄ array film presents a quite good transmittance modulation with 42% in the visible range and also shows good reaction kinetics with fast response time of about 2 s, much higher than those of the dense film (25% and 4.5 s). The better electrochromic performances of the porous film are attributed to its highly porous morphology, which shortens the ion diffusion paths and provides bigger surface area.     

Electrochromic properties of porous NiO thin film as a counter electrode for NiO/WO3 complementary electrochromic window

Highly porous nickel oxide (NiO) thin films were prepared on ITO glass by chemical bath deposition (CBD) method. SEM results show that the as-deposited NiO film is constructed by many interconnected nanoflakes with a thickness of about 20 nm. The electrochromic properties of the NiO film were investigated in a nonaqueous LiClO₄–PC electrolyte by means of optical transmittance, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements. The NiO film exhibits a noticeable electrochromic performance with a variation of transmittance up to 38.6% at 550 nm. The CV and EIS measurements reveal that the NiO film has high electrochemical reaction activity and reversibility due to its highly porous structure. The electrochromic (EC) window based on complementary WO₃/NiO structure shows an optical modulation of 83.7% at 550 nm, much higher than that of single WO₃ film (65.5% at 550 nm). The response time of the EC widow is found to be about 1.76 s for coloration and 1.54 s for bleaching, respectively. These advantages such as large optical modulation, fast switch speed and excellent cycle durability make it attractive for a practical application.     

Preparation of ordered mesoporous nickel oxide film electrodes via lyotropic liquid crystal templated electrodeposition route

A novel electrochemical route to fabricate ordered mesoporous metal oxide film electrodes has been investigated with particular reference to nickel oxide. Ordered mesoporous nickel oxide films are successfully synthesized by templated electrodeposition of H_I-e nickel hydroxide and followed by heat-treatment in air at various temperatures. The films are characterized physically by thermogravimetry (TG), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The applicability of this film as inexpensive and high-performance supercapacitor electrode material is demonstrated by the electrochemical characterization using cyclic voltammetry (CV) and chronopotentiometry technique. The specific capacitance of the nickel oxide film depends on the annealing temperature, showing a maximum value of 590 F g⁻¹ when the as-deposited film is heat-treated at 250 °C for 1.5 h.     

Electrochromic degradation in nickel oxide thin film: A self-discharge and dissolution phenomenon

Nickel oxide thin films known as optical active counter electrode in electrochromic devices were grown by Pulsed Laser Deposition (PLD) at room temperature (RT) under a 10⁻¹ mbar oxygen pressure. From intense electrochemical characterizations of as-deposited NiO electrodes in alkaline medium, a mechanism taking into account the three typical steps of their cycling life, namely the activation period, the steady state and the degradation period, is proposed. The reversible color change from transparent to brownish, generally ascribed to the Ni(II)/Ni(III) couple in the literature, was clearly identified to the electrochemically active nickel hydroxide/oxy-hydroxide phases. The reason lies in a spontaneous chemical conversion of NiO into Ni(OH)₂ when the film is immersed in KOH medium. Afterwards, once cycling is performed, there is in competition with the electrochemical process, a self-discharge phenomenon associated to a partial dissolution of the thin-film oxidized phases. This second process becomes predominant on cycling leading to a progressive degradation of the electrochromic performances.     

Multilayer porous Pd-doped SnO2 thin film: Preparation and H2 sensing performance

Porous pure and Pd-doped SnO₂ films are prepared using sol-gel synthesis with polystyrene (PS) microspheres as the template. Different characterizations are performed to analyze the microstructure and morphology of the films. The sensing performance of the films at various temperatures and hydrogen concentrations is investigated. Results show that high concentration of PS template significantly influences the continuity of films and the H₂ sensing performance. The porous SnO₂ film with 0.1 wt% PS microspheres exhibits the best performance. At 225 °C, the response magnitude of the porous 1 mol% Pd-doped SnO₂ thin film to 1000 ppm H₂ is 93.18, which is approximately 10.58 times of the pure sample.     

Enhanced high rate properties of ordered porous Cu2O film as anode for lithium ion batteries

Highly ordered porous Cu₂O film is electrodeposited on copper foil through a self-assembled polystyrene sphere template. Compared with the dense Cu₂O film and the octahedral Cu₂O powder, the ordered porous Cu₂O film exhibits an improved electrochemical cycling stability. The capacity of the porous Cu₂O film can maintain 336 mAh g⁻¹ and 213 mAh g⁻¹ after 50 cycles at the rate of 0.1 C and 5 C, respectively. The reversible capacity holds 63.4% as the discharge-charge rate even increases by 50 times. The enhanced high rate properties of the ordered porous film should be attributed to the sufficient contact surface of Cu₂O/electrolyte and the short diffusion length of Li⁺. Moreover, the direct contact between Cu₂O and current collector and the decreasing inactive interfaces of Cu₂O/polymer binder are also suggested as being responsible for the enhanced high rate property.     

胶体晶体模板法制备三维有序排列的大孔SiO2材料

将粒径为480 nm的聚苯乙烯微球离心组装为胶体晶体模板,以正硅酸乙酯为硅源配制SiO₂溶胶并填充到模板间隙,原位形成凝胶,最后通过焙烧去除模板,得到三维有序大孔（3DOM）SiO₂。通过SEM检测,大孔以六方有序的方式排列,其孔径及孔径收缩率分别为360 nm和25％。大孔之间由小窗口连通,构成内部三维交联的大孔网络。低温N₂吸附测试表明,大孔孔壁上存在中孔孔隙,其中在3～4 nm有一集中的孔分布。XRD显示,制备的3DOM材料由无定形SiO₂组成。     

Enhanced bolometric properties of nickel oxide thin films for infrared image sensor applications by substitutional incorporation of Li

This study aims to investigate the influence of substitutionally incorporated Li on sensing performance of nickel oxide films for bolometer applications by comparing Ni_1-xO and (Li_yNi_1-y)_1-xO films. From the results of structural analysis, it was confirmed that the film deposited from Li_0.2Ni_0.8O target contained Li which substitutionally occupies the Ni cation site while maintaining a cubic NiO structure. The substitutionally incorporated Li in nickel oxide can serve as an acceptor providing a hole carrier, like as a structural defect. However, in contrast to the structural defect, the substitutional incorporation of Li made it possible to increase the number of hole carriers in nickel oxide film while maintaining excellent film quality. In addition, the contact resistance with electrode was greatly reduced as a result of the substitutionally incorporated Li. These changes in structural and electrical properties lead to a significant reduction of 1/f noise arisen from the (Li_yNi_1-y)_1-xO film. As a result, the sensing performance of the (Li_yNi_1-y)_1-xO film as evaluated using the (α_H/n)^1/2/|β| value was nearly 10 times better than that of the Ni_1-xO film. Consequently, it can be concluded that the substitutional incorporation of Li can significantly improve the sensing performance of nickel oxide films for bolometer applications.     

Preparation and properties of porous ceramics from nickel slag by aerogel gelcasting

To further resource industrial solid waste, porous ceramics with high porosity were prepared by a gelcasting method using nickel slag and kaolin as raw materials and hydrophilic nontoxic SiO₂ aerogel as a gelling agent. The effects of nickel slag content, dispersant and solid content on the properties and microstructure of porous ceramics were investigated in detail in terms of density, compressive strength, porosity, phase composition and micromorphology. The results confirmed that a certain amount of nickel slag can effectively improve the porosity of porous ceramics, while the addition of dispersant can promote the flow of the slurry, enhanced the denseness of the raw billet and significantly improved the compressive strength. However, its excessive use had a negative effect on the ceramic density and porosity. At the same time, the solid content played a key role in the performance of porous ceramics prepared by gelcasting, and too much solid content was also not conducive to the generation of pores. When the nickel slag content was 55%, the amount of dispersant was 2%, and the solid content was 60 vol%, the porous ceramic had a better overall performance, the density of the porous ceramic was 510 kg/m³, the compressive strength was 1.3 MPa, and the porosity reached 80.1%. The major crystalline phases of porous ceramics prepared by nickel slag were cordierite and anorthite.     

X-ray absorption spectroscopy studies of nickel oxide thin film electrodes for supercapacitors

Nickel oxide films were synthesized by electrochemical precipitation of Ni(OH)₂ followed by heat-treatment in air at various temperatures (200-600 °C). Their structure and electrochemical properties were studied by cyclic voltammetry, X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS). XRD results showed that the nickel oxide obtained at 250 °C or above has a crystalline NiO structure. The specific capacitance of the oxide depends on the heat-treatment temperature, showing a maximum value at 300 °C. XAS results revealed that the non-stoichiometric nickel oxide (Ni_1−xO) approached the stoichiometric NiO structure with increasing heat-treatment temperature due to the defect healing effect. The defective nature of the nickel oxide could be utilized to improve its specific capacitance for supercapacitor application.     

Pseudocapacitive properties of electrodeposited porous nanowall Co3O4 film

A porous nanowall Co₃O₄ film is prepared by a facile cathodic electrodeposition. The as-prepared porous nanowall Co₃O₄ film shows a net-like porous structure with huge porosity. The porous network is made up of free standing interconnected Co₃O₄ nanoflakes with a thickness of 20 nm. As cathode material for pseudocapacitors, porous nanowall Co₃O₄ film exhibits weaker polarization, higher electrochemical reactivity and better cycling performance as compared to the dense Co₃O₄ film. The specific capacitance of porous nanowall Co₃O₄ film is 325 F g⁻¹ at 2 A g⁻¹ and 247 F g⁻¹ at 40 A g⁻¹, respectively, much higher than that of the dense Co₃O₄ film (230 F g⁻¹ at 2 A g⁻¹ and 167 F g⁻¹ at 40 A g⁻¹). The better pseudocapacitive performances of the porous nanowall Co₃O₄ film are attributed to its highly porous morphology, which provides large reaction surface and short ion diffusion paths, and relaxes the volume change caused by the reaction during the cycling process.     

Preparation of biomorphic porous zinc oxide by wood template method

This paper presents an effective method to fabricate highly porous zinc oxide (ZnO) derived from different wood templates, where the microstructure features of wood template were well reproduced in the final product. Biomorphic ZnO was fabricated via the sol–gel method by the infiltration of the precursor sol into the wood template and the sintering of wood template at high temperature under air atmosphere. Many characterization methods such as x-ray diffraction (XRD), scanning electron microscopy (SEM) and pore size analyzer detection were used to investigate the crystalline phase and microstructure of the product as well as the pore size of biomorphic ZnO. In our work, highly porous ZnO derived from different wood templates had been prepared. The relevant results revealed that the specie of wood template and sintering temperature played vital roles in the pore size, specific surface area and pore volume of the product.     

添加聚乙烯醇改善三氧化钨电致变色薄膜性能的研究

为改善三氧化钨薄膜的电致变色性能,采用钨粉过氧化聚钨酸溶胶-凝胶法制备了添加聚乙烯醇的三氧化钨电致变色薄膜.采用扫描电镜、紫外可见分光光度计和CHI电化学工作站分别测定和分析了三氧化钨薄膜的微观结构、光透过性能和循环伏安特性.结果表明,添加一定量的聚乙烯醇可使薄膜的结构更加平整,变色更为均匀;在着色态、褪色态下的光透过率之差达到60%以上,变色可调范围变大.电致变色可逆性能和光谱性能较不添加聚乙烯醇有所提高.     

Enhanced optoelectrical performance of ultraviolet detectors based on self-assembled porous zinc oxide nanostructures

A templated self-assembly technique was utilized in the present study to grow porous zinc oxide nanostructures. The nanostructures were formed by the electrochemical deposition of ZnO through the interstitial spaces between polymer microsphere templates. After the deposition, polymer microspheres were removed by dissolving in chloroform solvent, leaving porous ZnO nanostructures. This technique is benefited from facile controllability of the pore morphology and size by varying the diameter of microspheres. X-ray diffraction analysis showed a dominant peak corresponding to the hexagonal ZnO structure. Moreover, no significant structural strain was observed after the removal of spheres unlike the other synthesis methods of porous materials. The improved photoluminescence (PL) properties revealed an enhancement in the light capturing capability of the systems due to the multiple scattering of light in the pore walls. The porous sample showed a PL blue-shift compared to the flat one, indicating a reduction in crystallite size of ZnO nanostructures. To assess the photonic applications of synthesized porous ZnO substrates, a metal-semiconductor-metal photodetector was developed via the metallization of ZnO nanostructures, and their optoelectrical properties were tested under UV radiation. The results showed an improvement in photosensitivity and quantum efficiency of devices based on porous ZnO substrates which can be assigned to the larger exposed area and elevated rates of electron-hole generation in this sample.     

A flow model of porous anodic film growth on aluminium

The development of pores in a classical porous anodic film formed on aluminium in phosphoric acid solution is investigated. The study employs a tungsten tracer layer that is incorporated into the anodic film from the aluminium substrate, followed by detection of the tracer by transmission electron microscopy and Rutherford backscattering spectroscopy. Distortions of the tungsten layer on entry into the film and retention of tungsten species in the film are compatible with porosity arising mainly from flow of anodic oxide beneath the pore bases towards the cell walls. The behaviour is contrary to expectations of a dissolution model of pore formation.     

Preparation of CdS thin films by electrodeposition: effect of colloidal sulfur particle stability on film composition

CdS thin films of about 1 m thickness were deposited from an aqueous solution containing Cd²⁺, Na₂S₂O₃ and gelatin as the protective colloid to stabilize the size of colloidal sulfur at from 30 to 40 nm and keep the concentration to an appropriate value during electrolysis. The effects of concentrations of Cd²⁺ and S₂O₃ ^2– ions and the deposition potential on the composition of CdS films were studied. The reaction mechanism of CdS film formation on the electrode is discussed. CdS film, whose composition is uniform across the film and which does not contain excess metallic cadmium, can be deposited from a solution containing 0.50 to 2.00 mM Cd(NO₃)₂, 1.00 to 5.00 mM Na₂S₂O₃ and 1.0 × 10^–7 to 1.0 × 10^–3 wt % gelatin.     

简述胶晶模板法制备三维有序大孔炭材料

三维有序大孔炭(3DOM)材料是近年来刚刚兴起的多孔材料领域一项重要研究课题。3DOM大孔炭材料不仅具有多孔材料的一般特点,还具有孔结构排列周期性强、孔径分布窄、大孔尺寸均匀可调,且具有较大的孔径、较高的表面积等一系列特点,在新型催化、吸附分离、电极材料等方面都具有潜在的应用价值。本文总结了近年来胶晶模板法制备三维有序大孔炭材料,分别从模板的制备、碳源的选择以及到最终大孔炭的制备三个方面加以总结概述。     

Remarkably enhanced photocatalytic activity by nickel nanoparticle deposition on sulfur-doped titanium dioxide thin film

To enhance the photocatalytic performance of titanium dioxide, the structures of both bulk and surface were modified. Doping of sulfur atoms to be substituted for lattice oxygen atoms of titanium dioxide was carried out to extend the light absorption by atmosphere-controlled pulsed laser deposition, which allows direct preparation of impurity-included thin film such as sulfur-doped titanium dioxide. On the other hand, to enhance the surface catalytic reaction, nickel nanoparticles were deposited at the thin film substrate by chemical vapor reductive deposition method, which is a novel preparation technique of metallic nanoparticles on the substrate surface. Obtained sulfur-doped titanium dioxide was found to possess sensitivity to visible light with the wavelength up to 550 nm, indicating the photocatalytic activity in visible region. Sulfur doping induced the dye degradation activity under visible light irradiation. When nickel nanoparticles were deposited, a remarkable enhancement of the hydrogen evolution activity through ethanol decomposition of more than 20 times as much as unmodified titanium dioxide thin film was accomplished. In addition, the stability of sulfur atom doped into titanium dioxide structure was investigated.     

Enhanced thermoelectric performance in aluminum-doped zinc oxide by porous architecture and nanoinclusions

As a promising thermoelectric material, aluminum-doped zinc oxide (AZO) exhibits high thermal conductivity, which limits its use in high-temperature thermoelectric applications. Here, we report an effective route for forming a porous architecture and nanoinclusions by introducing nano-SiC to reduce the thermal conductivity. The simultaneous formation of a porous architecture and nanoinclusions promotes enhanced phonon scattering, resulting in fairly low thermal conductivity of approximately 3.3 W? m^?1? K^?1. Meanwhile, the Seebeck coefficient shows the significant improvement due to energy filtration effect caused by porous architecture and nanoinclusions. The resultant dimensionless figure of merit of approximately 0.2 at 1050 K was 1.5 times higher than that of AZO ceramic without nano-SiC, which is attributed to the combined factors of increased Seebeck coefficient and reduced thermal conductivity.     

Nanostructured materials prepared by use of ordered porous alumina membranes

We report on three different methods to prepare nanostructured materials using highly ordered porous alumina membranes as templates: (1) firstly, a new and simple method, termed as the paired cell method, was developed for the preparation of inorganic nanowires. Several kinds of inorganic nanowires were synthesized using this method. The structure and composition of these nanowires were determined by field emission scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray spectroscopy. (2) Secondly, highly ordered platinum nanowire arrays were prepared by electrochemical method with the help of porous alumina membrane templates. The structure and composition of these nanowire arrays were also characterized by various experimental techniques. The electrochemically active surface area of the nanowire arrays was determined by cyclic voltammetry based on hydrogen adsorption. Results showed that the platinum nanowire arrays exhibited a large surface area. (3) Finally, we also present a simple and reliable procedure for the preparation of highly ordered metal nanohole and nanopillar arrays, based on the anodic oxidation of aluminum and vacuum evaporation technology. The field emission scanning electron microscopic images revealed that these metal nanostructure arrays were highly ordered over a large area. The nanoimprinting of aluminum surfaces using the as-prepared chromium nanopillar arrays was demonstrated, resulting in periodic indentation on the aluminum surface.