Electrochemical science advances最新文献

Gold star (AuST), which is one of the important anisotropic gold structures, finds applications in catalysis, sensing, and photothermal therapy by virtue of its branches of high aspect ratio. The preparation of AuSTs can prove challenging as it requires stringent reaction condition(s) and solution composition including various chemical additives, which are not suitable for either disposal in the environment or use in health-related studies. Furthermore, these chemical additives often cover the gold surface and hence cause interferences in the applications of AuSTs. In this work, we have reported a proof of concept for preparing AuSTs of monodispersed size on glassy carbon electrodes by developing a simple electrosynthesis method using an aqueous acid solution of chloroauric acid in the absence of any chemical additive, structure-directing or surface-protecting agent. This electrosynthesis strategy was developed by understanding the corresponding electrocrystallization mechanism and designing a suitable potentiostatic pulse strategy. The current response per unit area of the gold content for the oxidation of N-Acetyl-L-cysteine was found to be superior on AuSTs compared to widely used citrate-capped gold nanoparticles (cit-AuNPs) and bare gold.

Lithium-Sulfur (Li-S) batteries as the next-generation battery system have an ultrahigh theoretical energy density. However, the limited conversion of polysulfides in sulfur cathodes deteriorates the performance of Li-S batteries. In this study, we develop a novel titanium nitride (TiN) catalyst for sulfur cathodes via atomic layer deposition (ALD). The synthesized ALD-TiN catalyst shows controllable ultrafine particle size (<2 nm) and uniform distribution at the nanoscale in the carbon matrix. Combined with electrochemical analysis and multiple post-characterization techniques, ALD-TiN demonstrates an excellent catalytic effect to facilitate the nucleation and deposition of Li₂S, which effectively suppresses the dissolution and shuttle of polysulfides. The as-prepared sulfur cathodes, with the assistance of TiN catalyst, exhibit excellent cycling performance at a high rate (4 C) and deliver 200% higher discharge capacity than the pristine Sulfur-pristine porous carbon composite cathodes.

The European Symposium on Electrochemical Engineering ESEE is organized by the Working Party on Electrochemical Engineering (WPEE) of the European Federation of Chemical Engineering every 3 years. The 12th ESEE, on June 14–17 2021, was planned at Wetsus European Centre of Excellence for Sustainable Water Technology in Leeuwarden but had, unfortunately, to be held online due to the COVID 19 pandemic.

The focus of the event was on “Electrochemistry for electrification and energy transition toward a sustainable future.” It captures the aims of the WPEE to showcase scientific advances in physical, chemical and biochemical routes toward a future where electrochemical engineering is part of a sustainable society, closing resource cycles and contributing to zero-pollution mobility and manufacturing. All around the rapid electrification of our society can be found, changing how we recover valuable resources in a more sustainable way, make chemical products, store energy, provide energy to our houses, and go from place to place. Increasingly we move from molecular building blocks and processes toward a world where the electron is the carrier of energy and information and is the key building block to create new materials.

The scientific program of the conference covered over 140 oral presentation and 25 posters, two tutorials and a match making session for academic and industrial researchers. Two important prizes of the WPEE were given and accompanied by award lectures: “Recognition for a Life Devoted to Electrochemical Engineering 2020 Award” to Professor Christos Comninellis and the “Carl Wagner Medal 2020” to Dr Emmanuel Mousset. Overall it was a very successful event, although we unfortunately could not meet in person and not visit beautiful Leeuwarden. This Special Issue is bringing together a small selection of contributions presented during the event. It was prepared thanks to collaboration of the journal editorial office and authors of the contributions and we hope, you will enjoy reading it.

We also would like to invite you to the 13th ESEE, which will be held in Toulouse from 26th to 29th of June 2023. Focus of the event is on the Electrochemical Engineering as the key enabling to overcome current societal problems regarding energy, environment, and life.

The authors declare no conflict of interest.

The present application note summarizes an advanced methodology that allows for deriving potential-dependent volcano curves for energy storage and conversion processes. The conventional approach relies on the combination of density functional theory calculations and scaling relations for a single mechanistic pathway as well as a discussion of electrocatalytic activity by means of the potential-determining step, determined at the equilibrium potential of the reaction. Herein, it is illustrated how several reaction mechanisms can be factored into the volcano curve and how the rate-determining step based on the descriptor G_max(U) can be derived by a rigorous thermodynamic analysis of adsorption free energies fed by a data-inspired methodology.

The activity of catalysts is mainly dictated by the adsorption strength of reaction intermediates at their surfaces. For electrocatalysts in solution, the adsorption strength is not only determined by the intrinsic properties of catalysts and reactants, but also by the solvation energy of reaction intermediates, which is difficult to capture with theoretical methods. Here, we report the impact of different explicit solvation approaches in estimating the stability of oxygenates on the (111) surface of platinum, widely used in oxygen electrocatalysis. We simulate the adsorption of OH, O, and OOH intermediates, relevant for oxygen reduction and oxygen evolution reactions, on Pt(111) with different solvation environments. We apply the static water bilayer model, typically adopted to calculate solvation energies on Pt(111) in computational studies. We then study the trend of solvation energies under different microsolvation environments, by adsorbing the intermediates in presence of an increasing number of water molecules. Last, we use a dynamic approach based on ab-initio molecular dynamics (AIMD) to account for dynamic effects. Our results indicate that the stabilities of oxygenates approach those of the water bilayer when the number of molecules increases from zero to three, but the free energies are affected in a not trivial way by the morphology and size of the water cluster, due to the increased complexity and configurational space. Moreover, static methods imply overcorrected free energies. The adoption of a molecular dynamics approach, based on single-run AIMD simulation of the Pt(111)/H₂O interface, allows retrieval estimates close to the experimental observation, including dynamic effects, and is highly transferrable. These results suggest that i) when using a microsolvation scheme, it is recommended to include a few water molecules, up to three to resemble the picture of the static bilayer model; ii) dynamic effects are important and can be included with a single-run AIMD scheme.

William W. Jacques was an American electrical engineer and chemist who designed in 1896 a very unusual fuel cell operated on solid (coal) fuel named by him a “carbon battery”. While the majority of fuel cells utilize gas (usually H₂) or liquid (e.g., ethanol) fuel, the “carbon battery” designed by Jacques was based on a carbon electrode operated as the fuel.

The battery consisted of 100 cells connected in series (Figure 1a) and placed on top of a furnace that kept the electrolyte temperature between 400–500°C (Figure 1b). The produced electrical output was 16 A at 90 V. Based on the experimental results, Jacques claimed ca. 82% efficiency for his carbon battery, but careful analysis considering the heat energy used in the furnace and the energy used to pump air (O₂ was an oxidizer) resulted in a much lower battery efficiency of ca. 8%.

Later research demonstrated that the current generated by his battery was not obtained through electrochemical reaction as suggested by Jacques, but rather through the thermoelectric effect. Several subsequent researchers have stated that Jacques's was the last notable attempt to derive electricity directly from coal.

The author declares that he has no conflict of interest.

Hans Wenking (Figure 1) was a German electrical engineer, physicist and inventor who devoted his lifetime to the development of electronic equipment for chemistry and physics, particularly constructing the first potentiostats, which became major parts of modern electrochemical instruments. He was the first who described the basic principles of potentiostats.

In 1952, Hans Wenking constructed an electronic amplifier for controlling an oscilloscope using a mirror galvanometer with the signals recorded on photographic paper. This amplifier was later used as a core of a new potentiostat with only a power supplier added. This potentiostat, being an important instrument for electrochemical investigations, was designed by Wenking during his work at the Max Plank Institute in Göttingen, Germany. At that time Hans Wenking was working in a group with Professor Karl Friedrich Bonhoeffer where he was appointed to develop a potentiostat that was needed for electrochemical experiments, particularly, for studying corrosion.

Until 1957, Wenking's potentiostat was manufactured only for the internal use of the Max Planck Institute in Göttingen. Later Hans Wenking together with Gerhard Bank established “Elektronische Werkstatt Göttingen” to commercialize the potentiostats. From 1959, the company operated under the name “Gerhard Bank Electronik”. Wenking designed the instruments as a freelance, but the brand “Wenking potentiostat” (Figure 2) soon became a famous trademark. The consequence of the potentiostat development was a rush in the development of electrochemical science. The phenomena of metal passivity could be better explained, including mechanisms of oxide layer formation, and far beyond the materials science. The potentiostat became a standard instrument for most electrochemical investigations, particularly for electroanalytical measurements.

Independent of Wenking's work, similar instruments were designed by other companies. Tacussel was one of those companies which came to a similar design as Wenking's potentiostats and started manufacturing potentiostats in France. In the USA, Wenking's potentiostats were leading on the market and became standard instruments in electrochemical labs.

Wenking has never published his results in scientific papers. On the other hand, Wenking never concealed the technical details of his instruments. The circuits and layouts designed by him were included in the operation manuals for the instruments, and even in some manuals, a detailed theoretical treatise was given. Wenking's instruments were always state-of-the-art and electrochemists of the 1950s–70s used them for many different applications.

In the 1920s–50s many polarographic and later voltammetric (e.g., cyclic voltammetry) measurements were performed using a two-electrode configuration composed of a dropping mercury electrode or any other small working electrode and a counter electrode, also serving as a reference. The two-electrode conf

John Edward Brough Randles (Figure 1) was an English electrochemist who made important contributions to the theoretical background of polarography, cyclic voltammetry, and electrochemical impedance spectroscopy. Many modern techniques of electrochemistry are descended from his work, including cyclic voltammetry, anodic stripping voltammetry, and various types of hydrodynamic voltammetry. The Randles-Ševčík equation applied on linear sweep voltammetry and cyclic voltammetry, and the Randles equivalent circuit used in the modeling of impedance spectra are named after him.

The earliest electrochemical work of Randles performed with an oscillopolarograph (cathode ray polarograph) resulted in the development of linear sweep voltammetry.^{[1, 2]} In addition to the experimental work, Randles solved a theoretical problem for expressing the current for diffusion-controlled electrochemical reactions by applying an ingenious graphical method.^[3]

Another important contribution of Randles to electrochemistry was in the theoretical analysis of Faraday impedance spectra published in 1947.^[4] The Randles equivalent circuit has been applied to the analysis of the impedance spectra including interfacial electron transfer (Faradaic component), capacitance and diffusion contributions to the impedance. It became the most frequently used theoretical treatment of impedance spectra. It should be noted that similar results were obtained by Russian scientists Dolin and Erschler in 1940, but the papers published in the Russian language have not been seen by the electrochemical community.

The Randles equivalent circuit (Figure 2) is one of the simplest and most common circuit models of electrochemical impedance. It includes a solution resistance, a double-layer capacitor, and a charge transfer or polarization resistance. While the Randles equivalent circuit is frequently sufficient for modeling simple electrochemical systems, it can be used as a starting point for more sophisticated models, for example, based on more resistances and capacitances organized in parallel or in a sequence.

It should be noted that John Randles was not only working on solving theoretical problems in electrochemistry, but he was a very good experimentalist. As an example of his experimental work, the Volta potential difference between a mercury droplet and an electrolyte solution measured by Randles can be mentioned.^[5] Notably, the great Russian electrochemist Alexander Frumkin had failed to obtain a stable and reproducible result for this kind of measurement.

Randles published relatively few papers, but many of them are of great importance and his theoretical treatments of electrochemical systems have been included in all electrochemistry textbooks.

The author declares that he ha

Porous electrodes are essential and high-performance components, which determine the performance of batteries, fuel cells, electrolysis cells, and further electrochemical devices. Improving their performance is a complex endeavor as the situation inside the electrodes is hard to grasp and control. This special collection brings together a series of valuable contributions regarding advanced experimental investigations and modeling studies of porous electrodes used in electrochemical devices for energy applications.

Porous electrodes should provide a sufficiently large surface area for the catalyzed reactions. Very often, the solid porous structure consists of several materials with very different functions such as catalytic activity and electronic or ionic conductivity. The pore system of these electrodes must be optimally designed for the transport of the various reacting species through diffusion, migration, and convection. Moreover, the presence of different phases (liquid electrolytes, gases) in the porous solid matrix of the electrodes leads to an extremely high complexity of the occurring processes. Obviously, there is a great need for improved experimental techniques for the determination of transport parameters and the precise characterization of the porous electrode structures. Based on this information, the development of detailed physicochemically based electrode models will allow for an optimal design of the porous electrodes with even better performance of energy-related electrochemical devices.

The overall 11 contributions in this collection cover different electrochemical applications such as lithium-ion batteries, carbon dioxide electrolysis, fuel cells, supercapacitors, and solar cells. In addition to experimental studies devoted to the characterization of the pore system and the determination of important performance parameters, improved models for electrodes and cells are another focus of this special issue. As guest editors appointed by Electrochemical Science Advances, we would like to thank all authors for their valuable contributions, the reviewers for their thoughtful comments, and the publisher Brian P. Johnson for his kind support. We do hope that this special collection on porous electrodes will provide some useful insights for the future development of improved technologies for energy storage and conversion.

The authors declare no conflict of interest.

Marcel Pourbaix (Figure 1) was a Belgian chemist (born in Russia) who greatly contributed to studies on corrosion. His biggest achievement is the derivation of potential-pH diagrams, better known as “Pourbaix Diagrams” (Figure 2a). Pourbaix Diagrams are thermodynamic charts constructed using the Nernst equation. They visualize the relationship between possible redox states of a system, bounded by lines representing the reactions between them under thermodynamic equilibrium. The Pourbaix diagrams can be read much like phase diagrams. In 1963, Pourbaix produced “Atlas of Electrochemical Equilibria in Aqueous Solutions” (Figure 2b), which contains potential-pH diagrams for all elements known at the time. Pourbaix and his collaborators began preparing the work in the early 1950s and continued the diagram updates over many years.

The author declares no conflict of interest.