高比容量二氧化钌电极材料制备

以无定型Ru O2·x H2O和金属Ru粉末为反应物,采用高温固相反应制备了Na型层状氧化钌(NaRu O2),通过离子交换反应对Na-Ru O2实现了剥离,得到了氧化钌纳米层胶体分散液。将氧化钌纳米层分散液冷冻干燥处理后得到了氧化钌重组物(ERRu O2)。通过XRD和SEM对制备试样进行了分析表征。电化学测试结果表明,在0.5 mol L-1H2SO4水溶液中,当电流密度为0.25 A g-1时,ERRu O2电极比电容高达645 F g-1,远远高于前驱体Ru O2·x H2O的比电容(367 F·g-1),并且ERRu O2电极表现出与前驱物相似的循环稳定性,是一种性能优异的超级电容器电极材料。     

Poly(1,5-diaminonaphthalene) films for supercapacitor electrode materials: effect of electropolymerization technique on specific capacitance

Poly(1,5-diaminonaphthalane) (1,5-PDAN) films have been successfully synthesized on pencil graphite electrode (PGE) from aqueous solution of 0.1 M monomer and 1.0 M perchloric acid (HClO₄) by different electrochemical techniques which are cyclic voltammetry (CV) and chronoamperometry (CA). The field emission scanning electron microscopy has been used to analyze the surface morphologies of 1,5-PDAN-coated PGE by CV (PGE/1,5-PDAN(CV)) and CA (PGE/1,5-PDAN(CA)). Electrochemical measurements have been performed to evaluate usability of the electrodes for supercapacitors using CV, electrochemical impedance spectroscopy (EIS), galvanostatic charge–discharge and repeating chronopotentiometry (RCP) methods in 1.0 M HClO₄. When compared the results of electrochemical measurements, it is concluded that PGE/1,5-PDAN(CA) has higher specific capacitance than PGE/1,5-PDAN(CV). Despite having high specific capacitance, long-term charge–discharge cycling stability of PGE/1,5-PDAN(CA) is lower than that of PGE/1,5-PDAN(CV). Additionally, electrodes exhibit high power and energy density, according to galvanostatic charge–discharge measurements. In conclusion, it can be said that PGE/1,5-PDAN(CV) and PGE/1,5-PDAN(CA) are promising materials for supercapacitor applications.     

Carboxyl-conjugated phthalocyanines used as novel electrode materials with high specific capacity for lithium-ion batteries

A novel molecular model of carbonyl-substituted phthalocyanine compounds used as the cathode material in a lithium-ion battery is demonstrated. Tetra-carboxyl and octa-carboxyl groups are substituted onto a phthalocyanine-conjugated system. The conductivities of phthalocyanine compounds are effectively improved by I₂ doping, without affecting the capacity and energy density. Taking lithium as the counter-electrode, the electrochemical properties of the microparticles are investigated, and the electrochemical mechanism of carboxyl groups substituted with phthalocyanines is analyzed. The results indicate that carboxyl-substituted phthalocyanines have high specific capacities. After 20 or 50 cycles, they still retain capacities of about 300 and 500 mA?·?h/g for tetra-carboxyl- and octa-carboxyl-substituted phthalocyanines, respectively. The multiple carbonyl groups and the large numbers of electrons on the phthalocyanine-conjugated system are the two factors contributing to the high specific capacity.

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Graphical Abstract A novel molecular model of carbonyl-substituted phthalocyanine compounds used as the cathode in a lithium-ion battery is demonstrated. Multiple carbonyl groups with high electrochemical activity are substituted onto a stable phthalocyanine-conjugated system, resulting in excellent conductivity and high specific capacity after using an iodine-doping technique; this could provide new ideas for electrode materials in lithium-ion batteries.

     

Highly mesoporous and high surface area carbon: A high capacitance electrode material for EDLCs with various electrolytes

Activated carbon fibers (ACFs) with high surface area and highly mesoporous structure for electrochemical double layer capacitors (EDLCs) have been prepared from polyacrylonitrile fibers by NaOH activation. Their unique microstructural features enable the ACFs to present outstanding high specific capacitance in aqueous, non-aqueous and novel ionic liquid electrolytes, i.e. 371 F g⁻¹ in 6 mol L⁻¹ KOH, 213 F g⁻¹ in 1 mol L⁻¹ LiClO₄/PC and 188 F g⁻¹ in ionic liquid composed of lithium bis(trifluoromethane sulfonyl)imide (LiN(SO₂CF₃)₂, LiTFSI) and 2-oxazolidinone (C₃H₅NO₂, OZO), suggesting that the ACF is a promising electrode material for high performance EDLCs.     

Facile synthesis of MXene/MnO2 composite with high specific capacitance

Journal of Solid State Electrochemistry - Ti3C2Tx is one of the typical MXene materials, where Tx stands for various surface terminations (OH, O, and/or F groups). In this paper, the delaminated...     

Long-term variation of capacitance of self-assembled alkanethiol films at polycrystalline Au electrode

Capacitance of a self-assembled hexadecanethiol monolayer (SAM) film increased in aqueous solutions and decreased in ethanol solutions with the time on a few hours scale. The increase and the decrease were demonstrated to be ascribed, respectively, to desorption and adsorption of hexadecanethiol. They obeyed approximately the first-order rate law for the amount of the adsorbed thiol. The SAM is in equilibrium with the 5 μM hexadecanethiol ethanol solution. The SAM becomes stable when it is immersed in deionized water for a long time or heated in the deionized water.     

Metal oxides composite electrode with high areal capacitance formed by thermal oxidation of stainless steel mesh

Journal of Solid State Electrochemistry - The motivation of this study is to understand the usability of annealed stainless steel mesh obtained by a straightforward method for energy storage...     

Crystallization of low and high molecular materials

For a better understanding of the crystallization of high molecular materials the paper starts with detailed statements as to the crystallization of low molecular materials. In this way it can be shown that there exist more properties in common than supposed before. This fact becomes evident from the thermodynamical point of view if the polymer is formally considered as a 2-components-system. In this system the stable rotational isomers, viz., the trans- and the gauche-form, are the components. In that case the crystallization process of linear polyethylene (HDPE) can be regarded as a crystallization of the trans-form in a trans-gauche mixture.In the paper the critical nuclei, which build up at the beginning of the crystallization and which have so-called equilibrium shapes, as well as the complete crystals, which have so-called growth shapes influenced by the kinetics of formation, are discussed. Special attention is paid to the lamellar growth because it often occurs in polymers. It is shown that the lamellar growth can be attributed to an activated sorption of foreign substances. In many polymers the role of the foreign substance is played by the gauche-form (autogenous activated sorption).By means of electron micrographs and calorimetric measurements of HDPE samples with a bimodal distribution of the lamellar thicknesses it could be proved that the melting range of polymers is due to a distribution of the lamellar thicknesses and apparently not to a changing conformational parts _Lk of the melting entropy as supposed by other authors [1]. Values from the literature for the conformational entropys _Lk of different polymers confirm in a good approximation thats _Lk can be compared to a mean entropy of mixing of the 2-components-model for polymers. This result makes evident that Flory's model for a polymer melt of interpenetrating chain coils can indeed be replaced, in a good approximation, by an ideal mixture of independent trans and gauche units in the sense of the 2-components-model. There follows in conclusion thats _Lk is a function of the gauche-trans ratio.Dedicated to Professor Dr. F. H. Müller. Presented at the Festive Colloquium, 7 May, 1982, in Marburg/Lahn, on the occasion of the 75th birthday of Professor Dr. F. H. Müller.Presented at the 14th Europhysics Conference on Macromolecular Physics, 21–24 September, 1982, in Vilafranca del Penedès (Barcelona), Spain.     

Determination of boron at low abundance levels in geological materials with a tetrafluoroborate-selective electrode

A modified procedure based on the tetrafluroborate-selective electrode is presented for the determination of low amounts of boron in geological materials. The main modifications are the use of hexamethylenetetramine as the buffer solution and a reduction of the temperature during measurement to 1–2°C to prevent hydrolysis; the latter precludes application of the usual method to solutions with low boron levels at very high total ionic strength. Satisfactory results can be obtained in the 10–200 μg g^?1 range (by using up to 250 mg of sample) without much sample handling. The method was tested for the analysis of terrestrial rhyolites (from Lipari/Italy, and Iceland) and tektites (thailandite, and Muong Nong-type tektites).     

Preparation of thick and hard coating films via sol–gel process with a low temperature treatment

SiO₂-polymer hybrid thick and hard coating films were successfully obtained via sol–gel process with a heat treatment at 200 °C. The films were achieved by control of hydrolysis and poly-condensation reaction of silica species. Key parameters were pH, water content and additional polymer in the coating solution. No-cracking and highly transparent films were formed with polymer content in a range from 28 to 42 mass% [vs. SiO₂]. Their thickness was varied from 2.6 to 3.5 μm with an increase in the polymer content. The haze values of the films after Taber abrasion were very low in a range from 1.3 to 2.7%, and the pencil hardness was over 9H. Moreover, no-damage was observed on the surface after steel wool abrasion with 4 kg loaded. These high mechanical strengths were come up to that of float glass, so that the coating films prepared by this process have a great potential for application to architectural and automotive window glass.     

Comparison of carbon aerogel and carbide-derived carbon as electrode materials for non-aqueous supercapacitors with high performance

Two porous carbon materials, one synthesised by pyrolysis of an organic aerogel prepared using sol–gel method and the other synthesised from molybdenum carbide by high temperature chlorination method, were tested as supercapacitor electrode materials in a non-aqueous tetraalkylammonium salt-based electrolyte. The gravimetric capacitance values calculated for the carbon aerogel (CAG)-based system were almost two times smaller (~55?F?g^?1) compared to carbide-derived carbon (C(Mo₂C))-based system (~125?F?g^?1). However, due to the very wide region of ideal polarizability, 3.6?V for C(Mo₂C) and 3.8?V for CAG-based test cells, very high energy densities up to 63?Wh?kg^?1 (34?Wh?dm^?3) and power densities up to 757?kW?kg^?1 (314?kW?dm^?3) were estimated for these systems, respectively. CAG-based system shows very short characteristic charge/discharge time constant values (0.05?s).     

Synthesis and characterization of low molecular mass luminescent liquid crystalline materials with 1,3,4-oxadiazole units

The synthesis, and liquid crystalline and photophysical properties of luminescent liquid crystalline compounds based on 1,3-bis[5-(4-alkoxyphenyl)-1,3,4-oxadiazole-2-yl]benzene (two-fold symmetry) I and 1,3,5-tris[5-(4-alkoxyphenyl)-1,3,4-oxadiazole-2-yl]benzene II (three-fold symmetry) are described. The mesophases were characterized using polarizing optical microscopy and differential scanning calorimetry. In addition, all compounds showed blue fluorescence with emission maxima between 366 and 382 nm, and good quantum yields of photoluminescence (Φ_PL = 45%).     

Facile preparation of ZrCO composite aerogel with high specific surface area and low thermal conductivity

A novel ZrCO composite aerogel is synthesized using zirconium oxychloride and resorcinol–formaldehyde (RF) as precursors through the sol–gel route and carbothermal reduction process. The effects of different Zr/R molar ratios and calcination temperatures on the physical chemistry properties of ZrCO aerogels are investigated. The ZrCO composite aerogel consists of the C/ZrO₂/ZrC ternary aerogel. The results show that with the increase of R/Zr molar ratios, the specific surface area and bulk density increase with calcination temperature up to 1300?°C, but decrease at even temperature (1500?°C). The specific surface area is as high as 637.4?m²/g for ZrCO composite aerogel (R:Zr?=?2:1), which was higher than ever reported. As the heat-treatment temperature increases to 1500?°C, the ZrC crystalline phase occurs and the t-ZrO₂ phase still appears within the composite. The thermal conductivity of the carbon fiber mat-reinforced composite aerogel is as low as 0.057?W/m/K at room temperature (25?°C).

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Decomposition of methane on polycrystalline thick films of Ga2O3 investigated by thermal desorption spectroscopy with a mass spectrometer

Methane in air can be detected by the conductivity increase of Ga₂O₃ films. Films (200 μm) of β-Ga₂O₃ were prepared by depositing a suspension of β-Ga₂O₃ powder (Johnson Matthey; 32102; 99,99%) on alumina substrates. The films were exposed to 20 kPa O₂ for 15 min at 934 K. In thermal desorption spectroscopy (TDS, β = 4,6 K/s, UHV conditions) only O₂ occured at temperatures above 934 K. On reduction in 100 Pa H₂ for 5 min at 800 K, only a suboxide, Ga₂O (above 880 K), indicating a destabilisation of the lattice [1], a broad hydrogen peak (440–930 K) and the formation of water (700–900 K) were observed. No Ga₂O₃ and O₂ were found in desorption. At temperatures between 260 K and 934 K the film was exposed to methane (100 Pa, 5 min). For exposure temperatures between 630 K and 934 K, CO, CO₂, H₂, and small amounts of CH₄ and the suboxide Ga₂O appeared in desorption. A reaction scheme for the decomposition of methane is proposed. It includes the adsorption of CH₄, the dissociation of CH₄, the desorption of H₂O and the formation of oxygen vacancies. These vacancies and the adsorbed hydrogen both acting as donors may explain the conductance increase on exposure to methane observed by other authors.     

Tube-covering-tube nanostructured polyaniline/carbon nanotube array composite electrode with high capacitance and superior rate performance as well as good cycling stability

The combination of a vertically aligned carbon nanotube array (CNTA) framework and electrodeposition technique leads to a tube-covering-tube nanostructured polyaniline (PANI)/CNTA composite electrode with hierarchical porous structure, large surface area, and superior conductivity. PANI/CNTA composite electrode has high specific capacitance (1030 F g⁻¹), superior rate capability (95% capacity retention at 118 A g⁻¹), and high stability (5.5% capacity loss after 5000 cycles). Energy storage characteristics of the PANI/CNTA composite are presented in this paper.     

Molecular design of prismane-based potential energetic materials with high detonation performance and low impact sensitivity

To develop new energetic materials, the eleven nitroester substitution derivatives of prismane were investigated at the B3LYP/6-311G** level of density functional theory (DFT). The gas phase heats of formation were calculated by isodesmic reactions and the solid-state heats of formation were obtained by the Politzer approach using the heats of sublimation for the designed compounds. The detonation velocities and pressures of all molecules were calculated by Kamlet–Jacobs equations based on molecular density and heat of detonation. The results show that the nitroester group in prismane is helpful for enhancing molecular detonation properties and power index. Among all molecules, 1,2,3,4-tetrnitroesterprismane has excellent detonation properties (detonation pressure = 40.05 GPa, detonation velocity = 9.28 km/s) and large power index value. The molecular stabilities were evaluated by calculating bond dissociation energies and characteristic heights (H₅₀). The results indicate that the bond dissociation energies of all molecules are above 80 kJ/mol, and all molecules have a larger H₅₀ value than hexanitrohexaazaisowurtzitane (CL-20, 12 cm). The obtained structure–property relationships may provide basic information for the molecular design of novel high-energy materials.     

Effect of sonochemistry: Li- and Mn-rich layered high specific capacity cathode materials for Li-ion batteries

Li- and Mn-rich layered Li_1.2Ni_0.13Co_0.13Mn_0.54O₂ cathode material was synthesized using sonochemical method followed by annealing at 700, 800, and 900 °C for 10 h. The material was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), Raman spectroscopy, and electrochemical techniques. Its performance as a cathode material for Li-ion batteries was examined. With the sample annealed at 900 °C, an initial specific capacity of 240 mAh g^?1 was obtained, which decreased to 215 mAh g^?1 after 80 cycles, thus retaining about 90 % of its initial capacity. In contrast, samples annealed at lower temperatures exhibited lower capacity retention upon cycling. Thus, the final annealing temperature was found to have a significant effect on the electrochemical stability of this material in terms of capacity, average voltage, and rate capability. The advantage of this synthesis, which includes a sonochemical stage, compared with a conventional co-precipitation synthesis, was also confirmed.     

Homogenizing the sulfonic acid distribution of DMF-modified PEDOT:PSS films and perovskite solar cells

Inverted perovskite solar cells using pristine PEDOT:PSS as the hole-transporting layer(HTL) have been widely studied for its less hysteresis and low-temperature preparation technologies. However, this device suffers from an inferior open-circuit voltage(V_(OC)) and stability problems. Several attempts have made on film formation and interface engineering to improve the efficiency. Modification proved beneficial to decrease energy offset at the interface between the HTL layer and the adjacent perovskite layer. In this paper, modification PEDOT:PSS layers were realized with a dimethyl formamide(DMF) solvent. The sulfonic acid distribution was homogenized in the normal direction after modification. The work function of the modified PEDOT:PSS layers increased from 4.71 to 5.07 eV, and the conductivity of modified PEDOT:PSS increased from 3 × 10~(-4) to 0.45 S/cm. The as-deposited perovskite films were more uniform with larger grain sizes and less pinholes, resulting in an improved VOCfrom 0.93 to 1.048 V, while the efficiency was increased from 11.5% to 16.8%. Solar cells without encapsulation under the 50 h and 50% humidity aging test showed 7% degradation of fill factor(FF) with 50 v/v% PEDOT:PSS layer, while the fill factor decreased 11.2% in the 0 v/v% PEDOT:PSS layer, respectively.     

Quartz Crystal Microbalance monitoring the real-time binding of lectin with carbohydrate with high and low molecular mass

A Quartz Crystal Microbalance (QCM) was used to monitor the mass changes on a quartz crystal surface containing immobilized lectins that interacted with carbohydrates. The strategy for lectin immobilization was developed on the basis of a multilayer system composed of Au–cystamine–glutaraldehyde–lectin. Each step of the immobilization procedure was confirmed by FTIR analysis. The system was used to study the interactions of Concanavalin A (ConA) with maltose and Jacalin with Fetuin. The real-time binding of different concentrations of carbohydrate to the immobilized lectin was monitored by means of QCM measurements and the data obtained allowed for the construction of Langmuir isotherm curves. The association constants determined for the specific interactions analyzed here were (6.4 ± 0.2) × 10⁴ M^− 1 for Jacalin–Fetuin and (4.5 ± 0.1) × 10² M^− 1 for ConA–maltose. These results indicate that the QCM constitutes a suitable method for the analysis of lectin–carbohydrate interactions, even when assaying low molecular mass ligands such as disaccharides.