Institute of Electrochemistry and Energy Systems

The PtRu/C HOR catalyst weakens the metal–H interaction and boosts the cell performance of the APEFC to 1 W cm⁻².

The oxygen evolution reaction (OER) is a key process that enables the storage of renewable energies in the form of chemical fuels. Here, we describe a catalyst that exhibits turnover frequencies higher than state-of-the-art catalysts that operate in alkaline solutions, including the benchmark nickel iron oxide. This new catalyst is easily prepared from readily available and industrially relevant nickel foam, and it is stable for many hours. Operando X-ray absorption spectroscopic data reveal that the catalyst is made of nanoclusters of γ-FeOOH covalently linked to a γ-NiOOH support. According to density functional theory (DFT) computations, this structure may allow a reaction path involving iron as the oxygen evolving center and a nearby terrace O site on the γ-NiOOH support oxide as a hydrogen acceptor.

An approach to the industrial-scale conversion of CO₂ through electrolysis is realized in this work. Such a device is fully based on alkaline polymer electrolytes, both as the membrane and the ionomer inside electrodes, and works only with pure water. Typical current density is 500 mA cm⁻² @ 3V 60 °C, with the faradaic efficiency of CO production over 90%.

We describe a synthetic procedure for preparation of large quantities of monodisperse thiol-stabilized gold colloids in toluene solution. The method is based on the solvated metal atom dispersion technique (SMAD), which is very suitable for preparation of large amounts of metal colloidal solutions, as well as of metal sulfide, metal oxide, and other types of dispersed compounds in different solvents. A combination of two different solvents like acetone and toluene is used for the preparation of the gold colloids. The necessity of initially carrying out the SMAD reaction in acetone comes from its high degree of solvation of gold particles. Acetone acts as a preliminary stabilizing agent. After its removal from the system, the particles are stabilized by dodecanethiol molecules, which enable their very good dispersion in toluene solution. A digestive ripening procedure is carried out with the gold-toluene colloid, and for this purpose pure toluene as solvent is necessary. This has a dramatic effect on the narrowing of particle size distribution and almost monodisperse colloids are obtained (some discussion of the probable mechanism of this remarkable digestive ripening step is given). These colloidal solutions have a great tendency to organize in two- and three-dimensional structures (nanocrystal superlattices, NCSs). We believe that this procedure provides a real opportunity to synthesize large amounts of gold nanocrystals as well as NCSs.

Memristive technology has been rapidly emerging as a potential alternative to traditional CMOS technology, which is facing fundamental limitations in its development. Since oxide-based resistive switches were demonstrated as memristors in 2008, memristive devices have garnered significant attention due to their biomimetic memory properties, which promise to significantly improve power consumption in computing applications. Here, we provide a comprehensive overview of recent advances in memristive technology, including memristive devices, theory, algorithms, architectures, and systems. In addition, we discuss research directions for various applications of memristive technology including hardware accelerators for artificial intelligence, in-sensor computing, and probabilistic computing. Finally, we provide a forward-looking perspective on the future of memristive technology, outlining the challenges and opportunities for further research and innovation in this field. By providing an up-to-date overview of the state-of-the-art in memristive technology, this review aims to inform and inspire further research in this field.

Carbon defects tune the formation of NiFe LDH nanodots confined in the mesopores of a macro–mesoporous carbon substrate, forming a hybrid electrocatalyst with excellent bifunctional performance for oxygen evolution and reduction reactions.

Artificial neurons and synapses are considered essential for the progress of the future brain-inspired computing, based on beyond von Neumann architectures. Here, a discussion on the common electrochemical fundamentals of biological and artificial cells is provided, focusing on their similarities with the redox-based memristive devices. The driving forces behind the functionalities and the ways to control them by an electrochemical-materials approach are presented. Factors such as the chemical symmetry of the electrodes, doping of the solid electrolyte, concentration gradients, and excess surface energy are discussed as essential to understand, predict, and design artificial neurons and synapses. A variety of two- and three-terminal memristive devices and memristive architectures are presented and their application for solving various problems is shown. The work provides an overview of the current understandings on the complex processes of neural signal generation and transmission in both biological and artificial cells and presents the state-of-the-art applications, including signal transmission between biological and artificial cells. This example is showcasing the possibility for creating bioelectronic interfaces and integrating artificial circuits in biological systems. Prospectives and challenges of the modern technology toward low-power, high-information-density circuits are highlighted.

Up to now, the positive lead ioxide active mass (PAM) has been treated as a crystal system. Its behavior, however, could not be fully explained by its crystal nature. In the present paper, a new approach is suggested which views PAM as a gel-crystal system. Crystal zones are built of PbO~. and exhibit electron conductivity. Gel zones are composed of hydrated lead dioxide, PbO(OH)~, that forms linear polymer chains. These allow electrons to move in the gel hopping from one Pb 4§ ion to the other along the polymer chain and from one polymer chain tothe other between the crystal zones. This determines the electron conductivity of the gel. Besides, PAM seems to meet all requirements of a good proton (ion) conductor. This gel-crystal structure of PAM explains more deeply its electrochemical behavior during charge, discharge, and overcharge as well as the relation between PAM crystallinity and polarization and plate capacity. When the positive active mass (PAM) of lead-acid battery plates is prepared from chemically obtained PbO2, its ca-pacity is low. If PAM is produced by electrochemical meth-ods, the capacity is high. It has also been established that PbO2 in PAM cannot be quantitatively determined by the x-ray diffraction method. These oddities of PAM have not

SnS–C nanocomposite can deliver a high capacity (568 mA h g⁻¹) for Na storage based on the conversion and alloying reaction.

characterization experiments and density functional theory calculations indicate that the interactions of the O, H, and OH species with the Ni surface under the h-BN shell are weakened, which helps to maintain the active metallic Ni phase both in air and in the electrolyte and strengthen the HOR processes occurring at the h-BN/Ni interfaces. These results suggest a new route for designing high-performance non-noble metal electrocatalysts with encapsulating two-dimensional material overlayers for HOR reactions.

A cycle-stable sulfur electrode in carbonate-based electrolytes is developed by embedding S/C nanoparticles in the PAN-based nanofibers.

For the first time, CaV6O16·3H2O (CVO), synthesized via a highly efficient and fast microwave reaction, is used as a cathode material for aqueous zinc-ion batteries. Ex situ X-ray diffraction confirms the structure of this material to be stable upon reversible Zn2+ intercalation, due to its large interlayer distance (8.08 Å). The pillaring effect of calcium makes the as-prepared CVO an excellent Zn2+ cation host.

The dependence of the composition of the anodic layer, the electric capacity, and the current on the quantity of electricity passed on potentiostatic oxida-tion of lead in sulfuric acid are investigated. Oxidation runs were performed in the lead sulfate, the lead oxide, and the lead dioxide potential regions. I t was established that at all oxidation potentials the electrode is passivated by the formation of a dense crystal l ine layer after passing a given quant i ty of electricity. Subsequently this layer grows. If the oxidation takes place in the lead oxide region, tetragonal PbO and basic lead sulfate form during the growth of the anodic layer. On oxidation in the lead dioxide region, tetrag-onal PbO and ~-PbO2 form in the deposit (at--950 mV with respect to the Hg/Hg2SO4 electrode). At + 1000 and + 1100 mV after the formation of a-PbO~, PbSO4 is oxidized to ~-PbO2. The change in the composition on oxidation is due to change in ionic conductivity between the PbSO4 crystals. When the current through the anodic layer begins to be transported by O 2- at the lead/anodic layer interface, tetragonal PbO is formed. If the oxidation poten-

When a Pb/ electrode immersed in solution is subjected to polarization in the lead dioxide potential region (φ > 1.0 V vs. Hg/ reference electrode), is decomposed releasing oxygen. The aim of this investigation is to elucidate the mechanism of the reactions taking place on oxygen evolution. Linear‐sweep‐voltametric cycling according to various cycling programs has been performed, and the structure of the anodic layer has been examined through scanning electron micrscopy and x‐ray diffraction. It has been established that at potentials in the region 1.0 < φ < 1.3 V the electrode has passive behavior (i.e., only a weak current passes through it), and in the range 1.3 > φ > 1.6 V extensive oxygen evolution is observed (active potential zone). This oxygen evolution is a result of two consecutive electrochemical reactions. While the first reaction proceeds at (φ > 1.0 V and leads to the formation of OH radicals, the second takes place at (φ > 1.3 V. It is assumed that these reactions proceed in the hydrated layer of the lead dioxide. Both reactions are localized in a certain number of active centers in the hydrated layer. At (φ < 1.3 V, the products of the first electrochemical reaction block these active centers and hence the current decreases significantly. At φ > 1.3 V, the second electrochemical reaction proceeds, as a result of which oxygen is evolved due to oxidation of the OH radicals and consequent unblocking of the active centers. The electrode is activated, and the reaction resistance is the dominant rate‐limiting factor. The present contribution proposes a mechanism of the elementary processes that occur on oxygen evolution in light of the gel‐crystal structure of the layer. This mechanism involves the hydrated polymer chains in the gel layer.

Seawater electrolysis for hydrogen production is a sustainable and economical approach that can mitigate the energy crisis and global warming issues. Although various catalysts/electrodes with excellent activities have been developed for high-efficiency seawater electrolysis, their unsatisfactory durability, especially for anodes, severely impedes their industrial applications. In this review, attention is paid to the factors that affect the stability of anodes and the corresponding strategies for designing catalytic materials to prolong the anode's lifetime. In addition, two important aspects-electrolyte optimization and electrolyzer design-with respect to anode stability improvement are summarized. Furthermore, several methods for rapid stability assessment are proposed for the fast screening of both highly active and stable catalysts/electrodes. Finally, perspectives on future investigations aimed at improving the stability of seawater electrolysis systems are outlined.

Pitaya-like Sb@C microspheres are prepared successfully<italic>via</italic>a facile aerosol spray drying method, which present a high initial capacity, good capacity retention and high rate capability for Na-ion storage. Morphological evolution reveals that the maintenance of the pitaya-like configuration guarantees excellent electrochemical performance.

Sodium ion batteries attract extensive attention owning to their earth-abundant elements and potential of low cost. Low-cost FeS@C as anode was prepared from the practical perspective including the simple synthesis method and sufficient cycle stability (97.6%, 3000 cycles).

The formation of well‐ordered 2‐D metal adsorbate layers in the underpotential (UPD) range and 3‐D metal deposits in the overpotential (OPD) range on foreign substrates was studied in the model system Ag(hkl)/Pb2+ by in situ STM under defined potential control with lateral atomic resolution. "Real" and "quasi‐perfect" silver single‐crystal faces served as substrates. The results are discussed in comparison with electrochemical and morphological studies, in situ extended x‐ray absorption fine structure and grazing incidence x‐ray scattering investigations. It is shown that in situ STM provides an excellent atomic view of the different stages of UPD and electrocrystallization of lead on silver. The influence of the substrate on the 2‐D structure of UPD layers and on the kinetics of 3‐D nucleation and crystal growth is demonstrated. The results indicate directly a Stranski‐Krastanov mechanism of 3‐D nucleation and growth in this system.

Heterogeneous electron-transfer (ET) processes at solid electrodes play key roles in molecular electronics and electrochemical energy conversion and sensing. Electrode nanosization and/or nanostructurization are among the major current strategies for performance promotion in these fields. Besides, nano-sized/structured electrodes offer great opportunities to characterize electrochemical structures and processes with high spatial and temporal resolution. This review presents recent insights into the nanoscopic size and structure effects of electrodes and electrode materials on heterogeneous ET kinetics, by emphasizing the importance of the electric double-layer (EDL) at the electrode/electrolyte interface and the electronic structure of electrode materials. It is shown, by general conceptual analysis and recent example demonstrations of representative electrode systems including electrodes of nanometer sizes and gaps and of nanomaterials such as sp(2) hybridized nanocarbons and semiconductor quantum dots, how the heterogeneous ET kinetics, the electronic structures of electrodes, the EDL structures at the electrode/electrolyte interface and the nanoscopic electrode sizes and structures may be related.

A temperature-responsive cathode is developed by coating an ultra-thin layer of poly(3-octylthiophene) in between an Al substrate and cathode-active layer.