A mini review on nickel-based electrocatalysts for alkaline hydrogen evolution reaction

High gravimetric energy density, earth-abundance, and environmental friendliness of hydrogen sources have inspired the utilization of hydrogen fuel as a clean alternative to fossil fuels. Hydrogen evolution reaction (HER), a half reaction of water splitting, is crucial to the low-cost production of pure H₂ fuels but necessitates the use of electrocatalysts to expedite reaction kinetics. Owing to the availability of low-cost oxygen evolution reaction (OER) catalysts for the counter electrode in alkaline media and the lack of low-cost OER catalysts in acidic media, researchers have focused on developing HER catalysts in alkaline media with high activity and stability. Nickel is well-known as an HER catalyst and continuous efforts have been undertaken to improve Ni-based catalysts as alkaline electrolyzers. In this review, we summarize earlier studies of HER activity and mechanism on Ni surfaces, along with recent progress in the optimization of the Ni-based catalysts using various modern techniques. Recently developed Ni-based HER catalysts are categorized according to their chemical nature, and the advantages as well as limitations of each category are discussed. Among all Ni-based catalysts, Ni-based alloys and Ni-based hetero-structure exhibit the most promising electrocatalytic activity and stability owing to the fine-tuning of their surface adsorption properties via a synergistic nearby element or domain. Finally, selected applications of the developed Ni-based HER catalysts are highlighted, such as water splitting, the chloralkali process, and microbial electrolysis cell.

Open image in new window

     

二维纳米材料/环氧树脂复合涂层在腐蚀防护中的应用

二维纳米材料具有片层结构、致密的六方晶格、大的比表面积和优异的热化学稳定性等特点,是作为防腐涂层填料的最佳选择。本论文综述了二维纳米材料在腐蚀防护复合涂层领域的应用。首先介绍了二维纳米材料在环氧树脂防腐涂料的屏障保护作用、抑制保护作用和牺牲保护作用,然后阐述了常见二维纳米材料在环氧树脂防腐涂料中的应用途径和方式。此外,本论文还总结了二维纳米材料在防腐涂料应用中存在的分散、取向以及与金属基体的附着力等问题及其解决办法。最后,对二维纳米材料在环氧树脂防腐涂料中的应用进行了总结和展望。     

Gastroretentive delivery systems: a mini review

Various attempts have been made to develop gastroretentive delivery systems. For example, floating, swelling, mucoadhesive, and high-density systems have been developed to increase gastric retention time of the dosage forms. It is known that differences in gastric physiology, such as, gastric pH, and motility exhibit both intra-as well as inter-subject variability demonstrating significant impact on gastric retention time and drug delivery behavior. Nevertheless, some floating devices have shown promising results. In this paper, the gastric physiology and the reported intragastric delivery systems have briefly been presented.     

Convective assembly of two-dimensional nanosphere lithographic masks

We report the implementation in our laboratory of a simple variant device to control the convective assembly of colloidal particles on solid substrate. The device allows the control over the volume of solution, rate of withdrawal, height of the deposition plate relative to the substrate and the portion of the substrate to be covered with solution. Ordered array of polystyrene nanospheres of 450 nm diameter were successfully deposited on glass and used as reliable lithographic masks.     

新型二维纳米材料MXene的制备及在储能领域的应用进展

二维过渡金属碳(氮)化物(MXene)作为一类新型二维纳米材料,自2011年发现以来,由于其优异的物理化学性能得到了广泛研究。MXene除具有传统二维材料的优异性能外,其高的导电性、良好的润滑性及电磁性等特殊性能,已被广泛地应用于能量存储、催化、润滑、电磁屏蔽、传感器、水净化等领域,并取得了一定的效果和进展。本文综述了近年来国内外关于MXene材料的最新研究现状,归纳总结了MXene的结构、性能和制备方法,以及在锂离子电池、超级电容器等领域的相关成果,指出了目前研究存在的短板,并展望了未来的研究方向。     

Graphene: A novel carbon nanomaterial

This review analyzes what the term graphene means today, and examines graphene preparation and identification methods and its chemical properties. The applications of this novel carbon nanomaterial are briefly discussed.     

A review of the support tools for the process of assembly method selection and assembly planning

This paper reviews the substantial body of research into software and other tools to support the closely related methodologies of assembly system selection, design for assembly, and assembly planning. Reported research has led to the adoption of a number of tools in current use in manufacturing industry. Here, the scope of this research, and its practical applications, is considered with a view to identifying the application domain of each approach and support tool. The authors are led to the conclusion that there is a need for further research into a methodology for the initial selection of the assembly method (e.g. assembly line, fixed point assembly, etc), and that such a methodology should consider not only factors of product technology, but also the industrial environment where assembly is to take place. Further, a knowledge-based decision support tool could facilitate the application of this methodology, and expand decision support further into the selection of assembly planning methods for subsequent application.     

纳米ZnO材料的一种简单制备方法

采用简单的水浴加热法,在较低的温度下(90℃),以氯化锌(ZnCl2)溶液和氢氧化钠(NaOH)溶液为原料,仅通过简单的磁力搅拌制得了直径在80～120nm间的纳米ZnO花状产物,并应用SEM、XRD、TEM和PL分析手段,对样品的形貌结构和光致发光性能进行了表征,并对其生长机理进行了讨论。     

The yielding of a two-dimensional void assembly in an organic glass

This paper represents a first attempt to discuss the growth of groups of cavities in an isotropic polystyrene-like solid. Calculations are made on a two-dimensional array of cylindrical voids in a sheet of uniform thickness. Stresses and displacements throughout the solid are obtained by use of the finite element method for both uniaxial and biaxial loading conditions. Elastic perfectly-plastic and strain-softening-hardening material laws are considered. It is shown how groups of voids are much more easily formed than single separate voids. For a strain-softening-hardening constitutive law a craze formation mechanism is proposed and its stability examined.     

Biodesulfurization: a mini review about the immediate search for the future technology

A major concern among the environmental agencies includes the emission of sulfurous gas into the environment. Consequently, the oil agencies are in constant search of alternative processes aiming the reduction of sulfur content in fuels. One of the technologies commonly used is the hydrodesulfurization (HDS), but this is a high-cost process that also requires high temperature and pressure. A complementary alternative to HDS is biodesulfurization (BDS) involving the use of specific microorganisms to the removal of sulfur present in the carbon chain, using the oxidation pathway “4S”, in which there is cleavage of carbon–sulfur bond, and maintaining the calorific value of the organic molecule. The BDS is a low-cost technique when compared with HDS. For this process to occur, activation of specific enzymes is needed, which is controlled by dszABC genes. Therefore, strategies to optimize this process have been of great importance to the oil refineries. For decades, attempts to try to implement BDS in the industry have been made, but difficulties in obtaining satisfactory results led the researchers to seek new knowledge about this bioprocess. The need of more studies concerning implementation on an industrial scale of this process is evident, since this biotechnology is a promising alternative to refineries in the near future.     

Programming supramolecular assembly and chirality in two-dimensional dicarboxylate networks on a Cu(100) surface

We report a comparative study on the 2D self-assembly of two related ditopic benzoic acid species, which have similar shape and endgroups but different backbone symmetry. High-resolution scanning tunneling microscopy data reveal how the symmetry information of molecular building blocks is readily expressed in the resulting chiral or nonchiral supramolecular networks. The underlying square Cu(100) surface steers network orientation and accounts for carboxylate formation, resulting in an unusual intermolecular hydrogen bond motif. Our results demonstrate that symmetry and chiral resolution in 2D supramolecular assembly can be controlled via the design of functional molecules and choice of substrate.     

Synthesis, two-dimensional assembly, and surface pressure-induced coalescence of ultranarrow PbS nanowires

Ultranarrow (1.8 nm) PbS nanowires are synthesized in a single step, under benchtop conditions at relatively low temperature (90 degrees C). The nanowires exhibit a nearly perfect crystal lattice, high width uniformity, and tight side-by-side registry. Two-dimensional (2D) assembly over large areas (>15 microm2) is achieved using the Langmuir Blodgett method. The wire width can be readily controlled in the range 1.8-10 nm by a surface pressure-induced coalescence reaction, as monitored by transmission electron microscopy and Raman spectroscopy. The fluorescence of the 2D assembly shows strong polarization dependence along the long axis of the wires, making the system potentially suitable for orientation-sensitive devices.     

A review on graphene and its derivatives as the forerunner of the two-dimensional material family for the future

Journal of Materials Science - In 2004, Geim and Novoselov discovered two-dimensional graphene comprised of sp2 carbon atoms. Graphene is a thin layer of carbon consisting of excellent surface...     

Electrical-driven disaggregation of the two-dimensional assembly of colloidal polymer particles under pulse DC charging

Two-dimensional structures of polymer (polystyrene) colloidal particles were formed on a substrate by electrophoretic deposition in an aqueous suspension. The prepared suspension is stable for a few days; therefore, it was not necessary to place an additional mixing during the deposition process. The particle aggregation/disaggregation formation was observed on the metal surface in order to study the effect of pulse direct current (DC) charging in comparison with conventional DC charging. At the charging frequency of 80 Hz, it was observed that pulse DC charging with a maximum applied voltage of 3.3 V/cm (50% duty cycle) clearly reduced the degree of aggregation of particles having diameters of 50 and 300 nm comparing to those of DC charging. Pulse charging at high frequency is thus found to be more effective in preventing particle aggregation during electrophoretic deposition than conventional DC charging.