Electrochemical science advances最新文献

In this study, the electrochemical behaviour of phosphine in sulphuric acid solutions on the surface of various electrode materials was conducted by voltammetric investigations. The effects of electrode materials such as lead, copper, and platinum electrodes on the PH₃ anodic oxidation were investigated. Polarization curves were recorded by saturating the sulphuric acid solution with phosphine. The results received show that the electrochemical oxidation of phosphine on the lead electrode is accompanied by an oxygen evolution potential and, on the copper electrode, copper (II) ions show catalytic effects. The maximum anodic oxidation of phosphine on a platinum electrode was observed at the potential range of 0.8–1.0 V, and in the presence of copper (II) ions on the polarogram a maximum of phosphine oxidation is recorded at a potential of approximately 0.1–0.2 V.

Lactate is a useful analytical indicator in various fields. The lactate monitoring benefits from evaluating the body's condition, as excessive muscle use or fatigue can result in injury. Further, it is useful for alerting to emergencies like haemorrhage, hypoxia, respiratory distress, and sepsis. Additionally, the determination of the food's lactate level is very important in examining freshness, storage stability, and fermentation degree. Given such benefits, the determination of lactate in various samples has been widely explored, especially using electrochemical sensor technology. Despite enzymatic sensors being the focus of numerous studies, enzyme-free platforms have gained focus over the last few years to address the matter of enzyme stability. This review article respectfully offers an overview of the concepts, applications, and recent advances of electrochemical lactate detection platforms. A comparison of hot research for enzymatic and enzyme-free lactate sensors in terms of electrode surface engineering, enzymes and their immobilisation matrices, and several analytical parameters, including linear dynamic range, the limit of detection, sensitivity, and stability, have been discussed. In addition, future perspectives have been highlighted in this review.

Catalytic hydrogenation refers to the (often) metal-mediated addition of dihydrogen (H₂) equivalents to unsaturated compounds to form new element-hydrogen bonds. This conceptually simple reaction is ubiquitous in the production of a vast number of essential chemicals. Despite a growing recognition of the importance of sustainability in manufacturing, the use of fossil-derived hydrogen gas and precious metal catalysts in hydrogenation remains widespread. Electrochemical variants of these processes are an appealing alternative, especially those that can make use of sustainable Brønsted acids, more abundant electrode materials and renewable electricity. In this mini-review, we give a selective overview of electrochemical hydrogenation methodologies for N-heterocycles and some related substrates from the specific perspective of the synthetic chemistry made possible by this increasingly popular approach.

Consecutive development of materials, components, and ultimately, devices does not appear to be a promising strategy in CO₂ electroreduction because maintaining comparability and transferring results between idealized and application-oriented systems proves challenging. A modular cell design and tracking cell conditions via sensors may be a solution. We displayed a strategy to characterize gas diffusion electrode operating regimes in a flow cell with regard to different current density ranges, as well as the impact of the flow gap design. We revealed strong interdependencies between cell components, their functions as well as individual cells when integrated into a stack. Expanding the scope and resolution of experimental data made new information on the change of system parameters in flow cells accessible.

In the first part of this study, double layer (DL) capacitances of plane and porous electrodes were related to electrochemical active surface areas based on electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) measurements. Here, these measured data are described with equivalent circuit models (ECMs), aiming to critically assess the ambiguity, reliability, and pitfalls of the parametrization of physicochemical mechanisms. For microstructures and porous electrodes, the resistive–capacitive contributions of DL in combination with resistively damped currents in pores are discussed to require the complexity of convoluted transmission line ECMs. With these ECMs, the frequency-dependencies of the capacitances of porous electrodes are elucidated. Detailed EIS or CV data-based reconstructions of complex microstructures are discussed as impossible due to the blending of individual structural features and the related loss of information. Microstructures in combination with charge transfer reactions and weakly conducting parts require parameter-rich ECMs for an accurate physicochemical description of all physicochemical mechanisms contributing to the response. Nevertheless, the data of such a complex electrode in the form of an oxidized titanium electrode are fitted by an oversimplistic ECM, showing how easily unphysical parameterizations can be obtained with ECM-based impedance analysis. In summary, trends in how microstructures, charge transfer resistances and oxide layers can influence EIS and CV data are shown, while awareness for the overinterpretation of ECM-analysis is raised.

The increasing impact of industrialization on climate change, primarily due to the emission of greenhouse gases such as carbon dioxide (CO₂), underscores the urgent need for effective strategies for CO₂ fixation and utilization. Electrochemical CO₂ reduction holds promise in this regard, owing to its scalability, energy efficiency, selectivity, and operability under ambient conditions. However, the activation of CO₂ requires suitable electrocatalysts to lower energy barriers. Various electrocatalysts, including metal-based systems and conducting polymers like polyaniline (PANi), have been identified to effectively lower this barrier and enhance CO₂ reduction efficiency via synergistic mechanisms. PANi is particularly notable for its versatile interaction with CO₂, cost-effectiveness, stability, and tunable properties, making it an excellent catalyst option for CO₂ reduction reactions (CO₂RR). Recent advancements in research focus on enhancing PANi conductivity and facilitating electron transfer through metal and metal oxide doping. Leveraging PANi's π–π electron stabilization ensures high conductivity and stability, rendering it suitable for real-time applications. Strategic dopant selection and optimization of Lewis acid-base interactions are crucial for selective CO₂-to-hydrocarbon conversion. Tailored electrode modifications, especially metal/metal oxide-loaded PANi electrodes, outperform conventional approaches, underscoring the importance of catalyst design in advancing CO₂ electroreduction technologies. This review provides a comprehensive analysis of the systematic methodology involved in preparing PANi-modified electrodes and explores the enhancements achieved through the incorporation of metals and metal oxides onto PANi-modified electrodes. It highlights the superior efficiency and selectivity of CO₂RR facilitated by these modified electrodes through profound synergistic approach compared to conventional metal electrodes such as platinum.

Nano-sized bubbles (NBs: nanobubbles) have attracted attention in various fields such as physics, engineering, medicine and agriculture for fundamental and practical reasons. Atomic force microscopy (AFM) has revealed the occurrence of NBs and discovered their flattened shape. However, their dynamic behaviours have not yet been discussed much owing to the slow scanning speed. The existence of these energetically unfavourable structures is still controversial owing to the lack of studies on bubble-like behaviour of NB such as aggregation, growth and dissolution. Recently developed high-speed AFM (HS-AFM) can observe nano-interface phenomena at a speed of 0.5 frame s⁻¹. In this study, HS-AFM was applied to electrolytic H₂ NBs. We successfully observed NB nucleation, growth and dissolution during a potential scan. Image analysis revealed flattened nuclei with heights of less than 10 nm. The NBs remained stable for a short period after the hydrogen evolution stopped, and they rapidly dissolved at the anodic potential. As the potential sweep was repeated, the number of NB nuclei increased. This is the first study showing the dynamic motion of NBs during the potential sweep by AFM. Videos captured by HS-AFM make NB existence more certain. This research contributes not only to the NB study but also to the clarification of the gas evolution mechanism on electrodes.

This study aims to investigate the electrochemical properties of usnic acid (UA), a secondary metabolite commonly biosynthesized by a variety of lichen species, and its biosynthetic precursor methylphloroacetophenone (MPA). During cyclic and differential pulse voltammetry, well-defined anodic peaks were observed for UA and MPA in 0.04 M Britton–Robinson buffer solution (pH 5) containing 20% (v/v) acetonitrile. The absence of cathodic peaks during the reverse voltammetric scans revealed that both oxidation reactions are chemically irreversible. Scan rate studies demonstrate that UA oxidation is an adsorption-controlled process, whereas the oxidation of MPA molecules occurs as a diffusion-controlled process. For both molecules, the number of electrons transferred during the oxidation was calculated to be 3. Differential pulse voltammetry results demonstrate that the anodic peak for the two molecules is markedly influenced by the solution pH and the same numbers of protons and electrons are involved in the oxidation process of the molecules. Based on the evidence generated by the electrochemical studies, oxidation mechanisms are proposed for UA and MPA, which involves a two-step electron loss with a hydration reaction taking place in between. This study provides an understanding of the bioactivity mechanisms of these two natural products.

The dynamics of the structural changes in the electrochemical double layer at the interface between a Ag(111) electrode and 0.1 M KOH electrolyte have been probed using surface X-ray diffraction measurements. The X-ray measurements utilised a lock-in amplifier technique to obtain a time resolution down to the millisecond scale. Two potential step regions were explored in an attempt to separate the dynamics of the reversible adsorption/desorption of hydroxide species (OH_ad) and the subsequent cation (K⁺) ordering in the double layer. By probing different positions in reciprocal space, sensitive to different structural changes, the time-dependent response of the electrode surface was probed and time constants for the different associated processes were obtained.