Functional Carbazole Liquid‐Crystal Block Codendrimers with Optical and Electronic Properties

The synthesis and characterisation of a family of block codendrimers consisting of highly versatile mesogenic and carbazole‐containing 2,2‐bis(hydroxymethyl)propionic acid (bis‐MPA) dendrons are reported. The liquid‐crystal behaviour was investigated by means of differential scanning calorimetry, polarised‐light optical microscopy and X‐ray diffraction. Depending on the chemical structure of the constituent dendrons, the codendrimers show lamellar or columnar mesophases. On the basis of the experimental results, models both at the molecular level and in the mesophase are proposed. The physical properties of the block codendrimers derived from the presence of the carbazole moiety in their structure were investigated: photoluminescence in solution and in the mesophase, electrochemical behaviour and hole transport. Electrodeposition of carbazole dendrons afforded a globular supramolecular conformation in which the mesogenic molecular side plays a key role.     

Hierarchical Carbon Nanowire/Ni@MnO2 Nanocomposites for High-Performance Asymmetric Supercapacitors

A 3D hierarchical carbon cloth/nitrogen-doped carbon nanowires/Ni@MnO₂ (CC/N-CNWs/Ni@MnO₂) nanocomposite electrode was rationally designed and prepared by electrodeposition. The N-CNWs derived from polypyrrole (PPy) nanowires on the carbon cloth have an open framework structure, which greatly increases the contact area between the electrode and electrolyte and provides short diffusion paths. The incorporation of the Ni layer between the N-CNWs and MnO₂ is beneficial for significantly enhancing the electrical conductivity and boosting fast charge transfer as well as improving the charge-collection capacity. Thus, the as-prepared 3D hierarchical CC/N-CNWs/Ni@MnO₂ electrode exhibits a higher specific capacitance of 571.4 F g⁻¹ compared with those of CC/N-CNWs@MnO₂ (311 F g⁻¹), CC/Ni@MnO₂ (196.6 F g⁻¹), and CC@MnO₂ (186.1 F g⁻¹) at 1 A g⁻¹ and remarkable rate capability (367.5 F g⁻¹ at 10 A g⁻¹). Moreover, asymmetric supercapacitors constructed with CC/N-CNWs/Ni@MnO₂ as cathode material and activated carbon as anode material deliver an impressive energy density of 36.4 W h kg⁻¹ at a power density of 900 W kg⁻¹ and a good cycling life (72.8 % capacitance retention after 3500 cycles). This study paves a low-cost and simple way to design a hierarchical nanocomposite electrode with large surface area and superior electrical conductivity, which has wide application prospects in high-performance supercapacitors.     

Electrolytic PdMo deposits with high corrosion resistance in relation to palladium

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Preparation and performance of (Co,Mn)3O4 spinel coating on Crofer alloy by composite electrodeposition and step-heating thermal conversion

The preparation and performance improvement of the spinel coating on the surface of ferritic alloy is of wide interest for its application in the metallic interconnects of the solid oxide fuel cells (SOFCs). The Co Mn₂O₃ composite coating is prepared on the surface of the Crofer alloy by the composite electrodeposition method. A step-heating thermal conversion process is subsequently used to convert the composite coating into a spinel coating, while a direct-heating process is implemented as the control experiment. Isothermal oxidation tests are then carried out for the prepared samples in order to present the high temperature performance. Scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and area-specific resistance (ASR) are used to analyze the properties of the matrix and coatings. The experimental results reveal that the coatings by step-heating thermal conversion exhibit better performance of electrical conductivity and oxidation resistance than the coatings by direct-heating process. Furthermore, with the increase of oxidation time, the atomic proportion of Cr element diffusing to the surface of the matrix is maintained at about 3%–4% for the samples with spinel coatings by step heating, which effectively prevent the Cr volatilization in the matrix. The preparation of spinel coatings on the ferritic alloy by composite electrodeposition and step-heating thermal conversion is helpful to stimulate new ideas for the development of reliable and cost-effective metallic interconnect.     

Non‐destructive Patterning of Carbon Electrodes by Using the Direct Mode of Scanning Electrochemical Microscopy

Patterning of glassy carbon surfaces grafted with a layer of nitrophenyl moieties was achieved by using the direct mode of scanning electrochemical microscopy (SECM) to locally reduce the nitro groups to hydroxylamine and amino functionalities. SECM and atomic force microscopy (AFM) revealed that potentiostatic pulses applied to the working electrode lead to local destruction of the glassy carbon surface, most likely caused by etchants generated at the positioned SECM tip used as the counter electrode. By applying galvanostatic pulses, and thus, limiting the current during structuring, corrosion of the carbon surface was substantially suppressed. After galvanostatic patterning, unambiguous proof of the formation of the anticipated amino moieties was possible by modulation of the pH value during the feedback mode of SECM imaging. This patterning strategy is suitable for the further bio‐modification of microstructured surfaces. Alkaline phosphatase, as a model enzyme, was locally bound to the modified areas, thus showing that the technique can be used for the development of protein microarrays.     

Benefiting from information-rich multi-frequency AC voltammetry coupled with chemometrics on the example of on-line monitoring of leveler component of electroplating bath

Simultaneous application of multiple sinusoidal waveforms perturbations superimposed onto DC staircase step significantly enriches current response. The measured current is characterized by a matrix of data rather than a conventional voltammetric output in a form of a vector. This increase of the dimensionality of the current response and therefore the wealth of analytical information is achieved without compromising the time of analysis. The natural approach for compression of such data and extraction of relevant information is by utilizing multi-way chemometric decomposition techniques. An electroplating solution presents a very challenging analyte for electroanalysis as its constituents interact synergistically with each other during both the plating process and its simulation during electroanalysis. For some components the mechanism is not entirely understood. Therefore, the only way to benefit from the analytical data is by employing soft modeling. The electrode processes involving additives rely heavily on adsorption and, indirectly, on electron transfer kinetics for which AC voltammetry is an analytical technique capable of delivering informative signals. This paper presents a rigorous universal method for calculating and validating an exemplary multi-way calibration of a leveler component in a copper electroplating bath used in the semiconductor industry. The method presented employs comparatively Parallel Factor Analysis coupled with Inverse Least Squares Regression and multi-linear Partial Least Squares. The calibration training set consists of multi-frequency AC voltammetric data subjected to pretreatments aiming to select informative independent variables and exclude outliers.     

纳米晶枝CuAu 合金催化剂对二氧化碳电催化还原性能的研究

利用可再生清洁能源将CO₂转化为CO和其他小分子是合成含碳燃料的可观方法之一。间歇性可再生能源存储的重要策略之一是将二氧化碳进行电化学还原。选择具有高活性和稳定性的电催化剂对于电化学还原CO₂至关重要。在这项研究中,我们使用简单的电沉积方法合成了具有纳米晶枝状结构的CuAu合金电极。各项表征显示原子比约为1:1的CuAu纳米枝晶对CO₂的电化学还原具有出色的催化活性。合成的主要产物是H₂和CO,这是合成气体是合成天然气,氨和甲醇合成的中间体。电化学阻抗谱（EIS）测量表明,相对于Cu和Au电沉积催化剂,CuAu纳米晶枝状催化剂具有相对低的电荷转移阻力。CuAu纳米枝晶催化剂是一种具有潜在的转化CO₂为合成气体的高活性电催化剂。     

Investigation of Parameters Influencing Tubular-Shaped Chitosan-Hydroxyapatite Layer Electrodeposition

Tubular-shaped layer electrodeposition from chitosan-hydroxyapatite colloidal solutions has found application in the field of regeneration or replacement of cylindrical tissues and organs, especially peripheral nerve tissue regeneration. Nevertheless, the quantitative and qualitative characterisation of this phenomenon has not been described. In this work, the colloidal systems are subjected to the action of an electric current initiated at different voltages. Parameters of the electrodeposition process (i.e., total charge exchanged, gas volume, and deposit thickness) are monitored over time. Deposit structures are investigated by scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). The value of voltage influences structural characteristics but not thickness of deposit for the process lasting at least 20 min. The calculated number of exchanged electrons for studied conditions suggests that the mechanism of deposit formation is governed not only by water electrolysis but also interactions between formed hydroxide ions and calcium ions coordinated by chitosan chains.     

Speciation of Copper(II)-Betaine Complexes as Starting Point for Electrochemical Copper Deposition from Ionic Liquids

The application of ionic liquids for the dissolution of metal oxides is a promising field for the development of more energy- and resource-efficient metallurgical processes. Using such solutions for the production of valuable chemicals or electrochemical metal deposition requires a detailed understanding of the chemical system and the factors influencing it. In the present work, several compounds are reported that crystallize after the dissolution of copper(II) oxide in the ionic liquid [Hbet][NTf₂]. Dependent on the initial amount of chloride, the reaction temperature and the purity of the reagent, copper crystallizes in complexes with varying coordination geometries and ligands. Subsequently, the influence of these different complex species on electrochemical properties is shown. For the first time, copper is deposited from the ionic liquid [Hbet][NTf₂], giving promising opportunities for more resource-efficient copper plating. The copper coatings were analyzed by SEM and EDX measurements. Furthermore, a mechanism for the decomposition of [Hbet][NTf₂] in the presence of chloride is suggested and supported by experimental evidence.     

Process prediction of Ni–SiC coatings based on RBF-BP model

The preparation of Ni–SiC coatings using magnetic field-assisted jet electrodeposition under various plating settings is described in this study. A RBF-BP composite neural network with 4 × 4 × 4 × 7 × 10 × 1 was used to predict the corrosion resistance of Ni–SiC coatings prepared by employing different plating parameters. The results show that the fitting degree between the expected value and the actual value of the RBF-BP composite neural network is 0.97497. Moreover, the hybrid neural network can accurately predict the corrosion resistance of Ni–SiC coatings prepared under different process parameters. The corrosion weight loss of the coating is the lowest at the current density of 4 A/dm², a jet rate of 3 m/s, a SiC particle concentration of 8 g/L, and at a magnetic field intensity of 0.8 T, demonstrating its corrosion resistance under these conditions. According to the coating characterization analysis, the coating's grain size was significantly refined, and the surface was smoother with a high amount of uniformly sized SiC nanoparticles.