Electrochemical science advances最新文献

The adsorption of the perfluoro-sulfonic acid polymer of Nafion and ionic liquid (IL) of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide on the surface of Pt was investigated via voltammetric analyses, using stepped Pt single-crystal electrodes with (111) terraces and (110) steps, and surface-enhanced infrared absorption spectroscopy (SEIRAS) analyses using a Pt polycrystalline electrode. Sulfonate anion in Nafion was adsorbed on the stepped Pt single-crystal electrodes and suppressed the oxygen reduction reaction (ORR) activity by more than 50%, regardless of the terrace width. The IL molecules were preferentially adsorbed on the step sites through a simple IL coating procedure. The SEIRAS analysis indicated that the IL molecules were stable on the Pt surface throughout potential cycles, where the anionic moieties were in contact with the Pt surface and reoriented depending on the potential. The IL modification prior to Nafion coating mitigated ionomer adsorption on the Pt surface. However, the mitigation effect was not reflected in the ORR activity because water production led to IL desorption during the ORR activity measurement. Accordingly, IL modification is a promising method for improving the performance of Pt catalysts in polymer electrolyte fuel cells; however, further studies to prevent the leaching of IL are required for practical applications of this approach.

This article reviews non-mercury configurations that have hitherto been reported in the literature as the working electrodes applicable in polarographic measurements. The individual types, namely gallium, liquid amalgams, dropping electrolyte, and carbon fluid electrodes, together with a carbon paste-based assembly or even solid disc electrodes with a periodically renewable surface, are presented, discussed, and critically assessed with respect to their potential employment in the present day's electrochemistry and electroanalysis.

Fuel cells (FCs) have gained a prominent position in recent years within the scientific community and the energy market as an alternative to mitigate the inherent problems in the energy production based on fossil fuels such as the constant reduction of nonrenewable resources, greenhouse gas emissions, and climate change. The versatility of high temperature (HT) proton exchange membrane (PEM) FCs, together with their high efficiency and potentially better performance compared to their counterparts, makes them an excellent candidate to accelerate the transition to more environmental friendly energy sources and processes. In recent years, notable developments in this technology have been reported, focusing on the cell components in a planar arrangement, which is the predominant design for all PEM-FCs. Alternative designs are lagging, even though tubular and conical structures can eventually enhance the power density, decrease sealing areas, and reduce fabrication costs. A lack of information regarding the transition between geometries makes the development and evaluation process tedious and challenging for unconventional architectures. This manuscript describes the development of a novel HT-PEM-FC, pointing out the challenges faced during component manufacturing and the proposed tubular FC perspectives.

Lithium-ion batteries exhibit a well-known trade-off between energy and power, which is problematic for electric vehicles which require both high energy during discharge (high driving range) and high power during charge (fast-charge capability). We use two commercial lithium-ion cells (high-energy [HE] and high-power) to parameterize and validate physicochemical pseudo-two-dimensional models. In a systematic virtual design study, we vary electrode thicknesses, cell temperature, and the type of charging protocol. We are able to show that low anode potentials during charge, inducing lithium plating and cell aging, can be effectively avoided either by using high temperatures or by using a constant-current/constant-potential/constant-voltage charge protocol which includes a constant anode potential phase. We introduce and quantify a specific charging power as the ratio of discharged energy (at slow discharge) and required charging time (at a fast charge). This value is shown to exhibit a distinct optimum with respect to electrode thickness. At 35°C, the optimum was achieved using an HE electrode design, yielding 23.8 Wh/(min L) volumetric charging power at 15.2 min charging time (10% to 80% state of charge) and 517 Wh/L discharge energy density. By analyzing the various overpotential contributions, we were able to show that electrolyte transport losses are dominantly responsible for the insufficient charge and discharge performance of cells with very thick electrodes.

The electrochemical reduction of a series of substituted benzoquinone have been examined in ethaline chosen as an example of ionic deep eutectic solvent. Experiments show the importance of hydrogen-bonding interactions between the quinones or its intermediates and the solvent. The effects are notably visible on the values of reduction potentials that are much more positive in ethaline than in a molecular solvent like acetonitrile and by the small difference between the first and second reduction potentials. The amplitude of the stabilization increases with the donor character of the substituent. Concerning the second reduction, the peak currents are considerably smaller than those of the first reduction and almost disappear at high scan rates (above 50 V s⁻¹). This behavior could be explained considering a chemical step prior to the electron transfer that becomes the limiting step (CE mechanism). As a remarkable feature, the electron transfer kinetics remain fast despite the hydrogen-bonding interactions (k_s = 0.12–0.14 cm s⁻¹).

Foresee advanced and innovative strategies is a key approach and constitutes a cornerstone for accessing clean, affordable, and reliable energy to satisfy the world's increasing prosperity and economic growth. To this end, hydrogen energy technologies parade as promising sustainable solutions to the looming energy crisis at either the small or large industrial scale, which will enable to reduce significantly our dependence on conventional energy sources based on fossil fuels without increasing atmospheric CO₂ levels. Water electrolysis with renewable energy is one of the best solutions to produce hydrogen without CO_x (CO and CO₂) emissions. However, the practical realization of this elegant opportunity of paramount importance is facing several challenges, among which are: (i) the efficient design of cathode and anode catalytic materials exhibiting improved intrinsic and durable activity; (ii) the scale-up of the system for the large-scale hydrogen production through the electrochemical water splitting. This review puts these opportunities and challenges into a broad context, discusses the recent research and technological advances, and finally provides several pathways and guidelines that could inspire the development of groundbreaking electrochemical devices for hydrogen production. It also points out the materials design and preparation for the efficient electrochemical production of the molecular hydrogen in acidic and alkaline environments, from a simple electrolytic solution to the water splitting reaction, which is also considered in the process. Furthermore, the main technology keys for designing a reliable electrochemical system will be noticed.

Ion-sensitive field effect transistor (ISFET) sensor is a hot topic these years, playing the combined roles of signal recognizer and converter for (bio)chemical analytes. In this review article, the basic concept, origination, and history of the ISFET sensor are presented. In addition, the common fabrication processes, the most-used working principle (potentiometric, amperometric, and impedancemetric), and the techniques of gate functionality (physical, chemical, and biological) are discussed introducing the afterward signal transfer processes from ISFET to the terminals through different types of circuits. At last, the development and recent progress (until 2021) of ions and biomolecules (DNA molecules, antibodies, enzymatic substrates, and cell-related secretions or metabolism) were introduced together with the outlook and facing obstacles (Debye screening, the wearability of ISFET, the multiplexed detections) before the commercialization of ISFET. This review article emphasizes the advantages of the developed ISFET sensors as miniaturization, low-cost, all-solid, highly sensitive, and easy operation for portable and multiplexed detections.

Ionic Liquids (ILs) and deep eutectic solvents (DESs) are promising candidate electrolytes in electrochemical fields due to their excellent properties. They can absorb water from the environment quickly, the existence of water in ILs/DESs benefits or harms their performance depending on the purpose of the applications. Therefore, studies on the effect of water on the properties of ILs/DESs have received much attention in recent years. This mini-review provides an overview of the structure of the electrochemical interface in ILs/DESs incorporated with water by summarizing the information acquired from a variety of characterization technologies and simulations. Both our understanding of the interfacial structure and our perspective on further research in the field are presented.

The second law of thermodynamics leaves no doubt that life on planet Earth and its inherent substantial decrease in entropy is fundamentally based on mechanisms converting environmental free energy into the spatial and temporal order of metabolic processes. This argument holds for present life as much as it does for its very beginnings some 4 billion years ago. In this contribution, we try to strip down free energy conversion in extant life (known as “bioenergetics” to the biologists) to its basic principles with the aim to potentially retrodict the nature of the pre-biotic precursor which drove life into existence. We demonstrate that these basic principles are deeply rooted in aqueous electrochemistry and strongly rely on inorganic redox compounds. The question of life's emergence, generally considered to fall into the realm of organic chemistry, should therefore rather be recognized as an electrochemical problem and its ultimate elucidation will need to strongly implicate the community of electrochemical scientists.

Supercapacitors are a new brand of high-performance nanoengineered devices that match the high capacity of batteries for electric energy storage with the ability of dry capacitors for ultra-fast charging or discharging rates. Thus, supercapacitors are capable of simultaneously providing the high energy-density and high power-density, demanded in a plethora of biosensors and portable electronic devices. In this review, a variety of nanomaterials investigated for possible applications in novel supercapacitors have been evaluated including different carbon nanoforms, metal oxides or hydroxides, chalcogenides, carbides and phosphates, as well as organic redox species, conductive polymers, metal-organic frameworks, MXenes and others. Different strategies for boosting volumetric capacitance, power density and charge or discharge cycling stability of micro-supercapacitors (MSCs) designed from these materials have been reviewed and their application potential assessed. Special attention has been given to micro-supercapacitor's designs that are suitable for miniaturization and integration with flexible microcircuits for wearable and implantable biomedical devices, remotely rechargeable sensors, microprocessor-controlled data processing chips, biomorphic computing, smart phone communication, military, automotive applications and emerging technologies. The different strategies applied for MSCs design and fabrication, including femto-laser writing, photolithography, screen printing, stamping, inkjet printing, mask patterning and others, have been assessed. The exciting future perspectives of MSCs have been discussed.