Miniaturized Electrochemical Device from Assembled Cylindrical Macroporous Gold Electrodes

In recent years, various electronic devices, including micromachine technology (MEMS), have been developed by nanotechnology. Since electrodeposition in an aqueous solution does not require a vacuum environment, various microfabrication and epitaxial control using electrodeposition have been investigated. Therefore, it is important to precisely and rapidly control the nanoscale interface structure during the electrodeposition process, and it is essential to elucidate the reaction process in the small region.Various methods have been studied for in-situ observation. The scanning probe microscope have given a way for atomic-scale observation, which can be applied to electrochemical nucleation and growth processes in an aqueous solution. However, the conventional scanning probe microscopes (scanning tunneling microscope: STM, atomic force microscope: AFM) require a few minutes to measure a surface, making it difficult to catch up the dynamic nucleation.A high-speed scanning probe microscope has the potential to overcome both the temporal and spatial problems. Magnussen et al. invented the video-rate STM and observed electrochemical interfacial phenomena such as metal nucleation, adatom diffusion, and molecular adsorption [1]. On the other hand, High-speed AFM (HS-AFM) was studied for biological samples [2]. Therefore, it is applicable to the imaging of soft surfaces and weakly adsorbed specimens.Taking advantage of the features of HS-AFM, we have observed Cu [3] and Zn deposition and dissolution (Fig. 1) as well as electrolytic nanobubble evolution [4]. In may talk, I would like to present dynamic behaviors of electrochemical nucleation and growth.

In the future, when fossil fuels are exhausted, alternative energy sources will be essential for everyday needs. Hydrogen-based energy can play a vital role in this aspect. This energy is green, clean, and renewable. Electrochemical hydrogen devices have been used extensively in nuclear power plants to manage hydrogen-based renewable fuel. Doped zirconate materials are commonly used as an electrolyte in these electrochemical devices. These materials have excellent physical stability and high proton transport numbers, which make them suitable for multiple applications. Doping enhances the physical and electronic properties of zirconate materials and makes them ideal for practical applications. This review highlights the applications of zirconate-based proton-conducting materials in electrochemical cells, particularly in tritium monitors, tritium recovery, hydrogen sensors, and hydrogen pump systems. The central section of this review summarizes recent investigations and provides a comprehensive insight into the various doping schemes, experimental setup, instrumentation, optimum operating conditions, morphology, composition, and performance of zirconate electrolyte materials. In addition, different challenges that are hindering zirconate materials from achieving their full potential in electrochemical hydrogen devices are discussed. Finally, this paper lays out a few pathways for aspirants who wish to undertake research in this field.

Supported nanostructured electroactive materials are known to boost the efficiency of electrocatalytic processes. Although they can be fabricated by multiple methods, electrodeposition offers several advantages, since the nanostructures are grown on the final support. However, the electrodeposition of nanostructures in a reproducible way requires a full understanding of the electrochemical nucleation and growth mechanisms at the nanoscale. Recently, we have developed an approach based on using carbon coated TEM grids as electrodes. This way, by combining atomic-scale TEM characterization with electron tomography and electrochemical measurements, we have found evidence that has led us to suggest an electrochemical aggregative growth mechanism [1]. It includes nanocluster surface diffusion, aggregation and coalescence as important elementary steps of the electrochemical growth process [2,3]. Due to the high level of complexity of the problem and the small timescales and lengthscales which need to be considered, electrochemical and surface characterization techniques feature inherent limitations. Therefore, a complementary approach based on numerical simulations is being evaluated. We have introduced a novel modelling approach that couples a Finite Element Method (FEM) with a random walk algorithm, to study the early stages of nanocluster formation, aggregation and growth, during electrochemical deposition. This approach takes into account different factors: not only the overpotential, but the transport of active species and electrochemical kinetics are also evaluated, together with the surface diffusion and aggregation of adatoms and small nanoclusters [4]. The combined analysis of experimental and simulated data reveals that the relative surface mobility of nanoclusters compared to this of the adatoms plays a crucial role in the early growth stages. The number of clusters, their size and size dispersion are influenced more significantly by nanocluster mobility than by the applied overpotential itself. As a result, it is shown that a classical first-order nucleation kinetics equation cannot describe the evolution of the number of clusters with time, N(t), in potentiostatic electrodeposition. Instead, a more accurate representation of N(t) should consider, not only an induction time that precedes cluster formation, but also the balance between cluster formation and aggregation. We show that an evaluation of N(t), which neglects the effect of nanocluster mobility and aggregation, can induce errors of several orders of magnitude in the determination of nucleation rate constants. These findings are extremely important towards evaluating the elementary electrodeposition processes, considering not only adatoms, but also nanoclusters as building blocks.

In this paper bilayer thin films of 10CGO/8YSZ electrolyte with enhanced O2- conductivity composed of gadolinia doped CeO2 (Ce0,9Gd0,1O2-) and yttria stabilized zirconia 8 mol% Y2O3 doped ZrO2 layers were deposited by Pulsed Laser Deposition (PLD) using various numbers of pulses. This composite has supplementary function in electrochemical devices because 10 CGO can act as interdiffusion barrier with cathode materials. The structure and morphology of these thin films, having thicknesses smaller than 1µm, were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The XRD patterns exhibit cubic fluorite structure with a sharp (111) peak. The grain size was found to depend on the thickness. Optical characterization was carried out by spectroscopic ellipsometry (SE) using the Tauc-Lorentz model. Keywords: Laser ablation, Electrolytes, Bilayer Thin Films, Tauc - Lorentz Model, Electrochemical Fuel Cells Devices

ABSTRACTA combination of Electron Cyclotron Resonance (ECR) plasma, electrochemical, and chemical growth process were examined to synthesize dielectric surface passivation layers on InSb. The material properties of ECR-grown SiOxNyon InSb at temperatures from 30°C to 250°C were investigated. Composition analysis was done using Rutherford backscattering spectrometry (RBS) and elastic recoil detection (ERD). The electrical quality of the passivation layer was characterized with capacitance-voltage (C-V) measurements on metal-insulator-semiconductor structures over the frequency range from 1 kHz to 1 MHz. Sulfided layers, Si3ON2on InSb, and sulfided layers capped with S3ON2all exhibited good C-V properties consistent with interface state densities on the order of 1011/cm2-eV, and flatband voltages of magnitude less than 1 V. The difference in adhesion of Si3N4on InSb and the adhesion of Si3ON2on InSb was described in terms of the strength of the bonding at the dielectric-InSb interface. This work is the first to demonstrate passivation of an InSb surface with high-quality ECR silicon oxynitrides grown at room temperature.

Electropolymerization of indole (IN) in the presence of thiophene (Th) was followed by in situ and ex situ spectroelectrochemical studies. A correlation between absorbance (390 nm) and charge (at 600 mV) values indicated that oligomeric species were formed in solution, and similar results were found with in situ measurements. The increase in conductivity by the incorporation of Th into polyindole was about 60 times for a feed ratio n IN / n Th =1: 10 and 19 times for n IN / n Th =1: 1. Similar effects were also observed during in situ spectroelectrochemical measurements of copolymer formation. It was also found that the cyclic voltametry peak potentials for the electrogrowth of copolymer films were closely correlated to the conductivities of the corresponding films (measured separately by four-point probe method), thereby allowing us to use the peak potential currents to predict the final copolymer film conductivities during the electrochemical growth process. The T g value of the polymer also increased with the incorporation of Th. The results strongly suggest that IN and Th copolymerize on the electrode surface as well as in solution.

Growth of poly(2,5-dimethoxyaniline) coatings on low carbon steel

Polyaniline (PANI) films doped with hydrochloric acid have been electrochemically deposited on mirrorlike platinum electrode surfaces by a cyclic voltammogram method. The Raman spectra of doped PANI films were investigated by excitation with a 633‐ or 785‐nm laser beam. It was found that the overall features of the Raman spectra depend strongly on the film thickness, due mainly to that the doping level of PANI film increases during the film‐growth process. X‐ray photoelectron spectroscopic (XPS) analysis and ultraviolet (UV)‐visible absorption spectrum results also confirmed this finding. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 171–177, 2004

Polythiophene (Pth) films have been electrochemically deposited on mirror-like stainless steel (SS) (or gold) electrode surfaces by direct oxidation of thiophene in boron trifluoride diethyl etherate (BFEE) solutions at a constant applied potential of 1.3 V (vs. Ag/AgCl). The Raman spectra of Pth films have been investigated by excitation with a 514, 633 or 785 nm laser beam. The 633 nm laser beam was found to be the best among the three excitation lights tried for studying the doping level change of Pth film. The overall features of 633 nm excited resonance Raman spectra of as-grown Pth films depend strongly on film thickness. Raman and X-ray photoelectron energy spectroscopic (XPS) results and electrochemical studies demonstrated that the doping level of the Pth film increased with the increase of film thickness. Furthermore, successive cyclic voltammetric scanning was found to be a more effective approach than applying a constant positive potential for doping a thin compact conducting polymer film.

With rapid development of the global economy, increasing environmental pollution and the depletion of fossil fuels, there is a vital need for clean, sustainable and efficient sources of energy as well as new technologies allied with energy conversion and storage (1). Among many application fields, some of the most practical and efficient technologies for electrochemical energy conversion and storage are fuel cells, batteries and electrochemical supercapacitors. In recent years, these devices have attracted significant attention, each with recognized advantages. Driven by this need and the promise of the technology, significant progress in practical and theoretical research and development of these devices has taken place. One of the challenges of developing these electrochemical energy conversion and storage technologies is the use of low cost and readily available materials that possess complex requirements of different applications. To overcome obstacles of high costs of raw materials and avoid usage of depleting sources, bio-based carbon materials are believed to lead the next generation of many industries including aerospace, sports equipment and electrochemical devices due to their abundance, high chemical stability, electrical conductivity, low cost and non-toxicity, high specific surface area and wide operating temperature range (2). The feasibility of the carbon precursors in different electrochemical devices for practical applications including hybrid power sources in electrical vehicles, burst-power generation in electronic devices, back-up power sources, portable and stationary equipment has been demonstrated. Cellulosic fibers in nano and micro scale, the green and most abundant material, have eco-friendly attributes that are economically and technically feasible to replace man-made fibers (3). Carbonization of cellulose yields carbons, including charcoal, activated carbon and graphite fibers. The process comprises of introducing the fibers in an inert atmosphere, preheating and drying the fibers, treating the dried fibers up to a certain temperature at which they carbonize by evolution of a purging gas and finally cooling the carbonized residues (4). The produced carbon materials have been investigated as a potential material in different electrochemical devices and have proved to have prospect as electrode materials for supercapacitors, catalyst supports in fuel cells and membrane separators in lithium-ion batteries. In this project, bio-based cellulosic starting materials have been investigated as a candidate for supercapacitor electrode materials. The produced activated carbon materials upon carbonization of the cellulose fibers have been functionalized and characterized by different techniques to study the effect of the morphology and surface area of the carbonaceous residues on their performance in the electrochemical device. This work has been coupled with a range of electrochemical tests in two and three-electrode systems including cyclic voltammetry, electrochemical impedance spectroscopy and charge-discharge loop tests. The work highlights the importance of relating the different characterization techniques of the raw and produced materials and the effect of each on the performance of the activated carbons as electrode materials in supercapacitors.

Two electrodes in one are obtained based on a bottom-up approach leading to a fully integrated microelectrochemical cell with independently addressable coaxial electrodes, as described by A. Kuhn and co-workers in article 1500192. The inherent macroporosity ensures tunable high surface areas for both cylindrical electrodes, thus allowing efficient transport and conversion of electroactive molecules. Such coaxial architectures are desirable for miniaturized electrochemical devices such as (bio)fuel cells, supercapacitors or biosensors.

Electrochemical processes underlie the functioning of electrochemical devices for energy storage and conversion. In this paper, electrochemoinformatics is defined as a scientific discipline, a part of computational electrochemistry, dealing with the application of information technologies, specifically data science, machine learning (ML), and artificial intelligence, to solve problems related to electrochemical processes, including the development of materials and electrochemical devices. Electrochemoinformatics is closely related to chemoinformatics and materials informatics and relies on the technologies they use. The definitions and the basics of chemoinformatics and materials informatics are reviewed with an emphasis on the role of data science, data representation, the use of ML methods, and molecular and material descriptors. The third constituent part of electrochemoinformatics is full‐cell informatics, which deals with the performance and design of whole electrochemical devices. The article focuses on the use of electrochemoinformatics in battery science and technology (battery informatics), including the development of electrolyte and electrode materials, battery performance monitoring, modeling, and design. The scope and the main challenges facing electrochemoinformatics are discussed.

Dissecting graphene capacitance in electrochemical cell

Applied Chemistry is at the center of the translation of the basic knowledge in chemistry to the type of technologies, materials, energy systems, and processes involved in industrial activity that serve the contemporary society. The textbook has been developed as an all-encompassing, conceptual, and industry-based learning tool of undergraduate and postgraduate students of Chemistry, Chemical Engineering, Materials Science, Environmental Science, and related subjects. The focus of the book is towards industrial chemistry, applied application and problem solving, and not towards abstract descriptive or policy-oriented curricular models. The book has been organized in such a way that students can be able to move in a logical way starting with the basic principles and then to the more complicated applications in industries. Each unit will be built on enhancing theoretical knowledge and at the same time illustrate how these concepts work at chemical plants, laboratories, power plants, and materials industries. Classical laws and models are wherever suitably related with new trends in energy storage equipment, green catalysis, advanced materials, sustainable fuels, and water management in industries. Unit I: Foundations of Applied Chemistry & Thermodynamics All applied chemistry branches need this unit to give them the conceptual and mathematical knowledge they need. It presents the breadth, the interdisciplinary character, and the industrial importance of chemistry, and then proceeds to discuss in detail the states of matter, and how they are important in the process of chemical processing. The thermodynamic, entropy, and free energy laws are presented in the framework of the feasibility of the reactions, energy efficiency, and maintenance of the equilibrium. They also consist of phase equilibria and metallurgical processes to ensure that students learn the behavior of materials in high-temperature and multi-phase industrial systems and have a sound foundation upon which to build their further higher-level work with. Unit II: Chemical Kinetics & Catalysis These unit dwells on rate and mechanism of chemical reactions that are vital to industrial productivity and safety. Basic kinetic principles, rate laws, and temperature influences are built up and issues that influence reaction rates. Catalysis is then further discussed, such as heterogeneous industrial catalysts, biochemical catalysts through enzyme catalysis and catalytic approaches in green chemistry. The focus is put on reaction optimization, selectivity, catalyst efficiency, and environmental impact, allowing students to enjoy the role played by chemistry in industrial innovation. Unit III: Electrochemistry & Surface Phenomena This unit puts emphasis on the role of the electrochemical and interfacial process in converting energy, protecting materials and industrial synthesis. The electrochemical cells, batteries, fuel cells, corrosion mechanism, electroplating and electrorefining are covered with industrial examples. They include adsorption and surface catalysis to describe the nature of heterogeneous reactions and separation processes. Students are prepared with knowledge to grasp contemporary energy technologies, prevention techniques on corrosion and mass production system in electrochemical processes through the unit. Unit IV: Colloids, Surfactants & Industrial Materials Physical chemistry Unit IV connects with materials science and formulation technology. It includes colloids, surfactants, micelles, and emulsions with a special focus on their use in pharmaceuticals, food technology, cosmetics, paints, detergents, and nanomaterials. It also offers a comprehensive study of cement, glass, and ceramics in terms of composition, manufacturing process, structure property relationship, and industrial application. This unit assists the students to know how chemical principles control the design and performance of structural and functional materials. Unit V: Fuels & Industrial Water Chemistry The last section will discuss two most important elements of industrial chemistry which are energy and water. It talks about solid, liquid, gaseous and other alternative fuels in terms of composition, calorific value, combustion efficiency, and environmental impact. Industrial water chemistry deals with impurities, analysis, treatment of water, softening, and boiler water issues. They have a focus on scaling, corrosion, energy efficiency, and sustainable resource management, which prepares students to meet real-world challenges of the industrial world. Pedagogical Features of the Book Clear explanation of fundamental principles with industrial linkage.Emphasis on process chemistry and applied problem-solving.Inclusion of industrial examples, reaction schemes, and practical relevance.Suitable depth and rigor for UG and PG level learning.Useful for university examinations, competitive exams, and industry-oriented studies. Overall Aim The main purpose of the book is to build the good conceptual base along with the industrial understanding, which helps the students to fill the gap between chemistry in the classroom setting and the chemical technology at the real world. Combining theory and practice, this textbook can be considered as an effective source of information to students, teachers, and practitioners working in the field of applied and industrial chemistry.

Fe/Co doped ZIF derived nitrogen doped nanoporous carbon as electrode material for supercapacitors