Current Opinion in Electrochemistry最新文献

Interfacial science and electroorganic syntheses are inextricably linked because all electrochemical reactions occur at the interface between the electrode and the solution. Thus, the surface chemistry of the electrode material impacts the organic reaction selectivity. In this short review, we highlight emergent examples of electrode surface chemistries that enable selective electroorganic synthesis in three reaction classes: (1) hydrogenation, (2) oxidation, and (3) reductive C–C bond formation between two electrophiles. We showcase the breadth of techniques, including materials and in-situ characterization, requisite to establish mechanistic schemes consistent with the observed reactivity patterns. Leveraging an electrode's unique surface chemistry will provide complementary approaches to tune the selectivity of electroorganic syntheses and unlock an electrode's catalytic properties.

This opinion addresses a basic impossibility to use Ni-containing and similar mediator electrocatalysts for fuel cell anodes if the fuel is organic, and air (or oxygen) is the oxidant. The reason is that oxidation onset potential is always higher than O₂/H₂O equilibrium potential. These anodes can operate in fuel cells with peroxide, but the voltages reported for direct urea peroxide fuel cells demonstrate contradiction with urea oxidation onset potentials. Ni-containing anodes for “boosting” in water electrolysis and in electrochemical reforming present more heathy research branch.

Flexible and wearable electronics are poised to revolutionize various domains, but the practical implementation of these devices is hindered by the significant difficulty of energy storage devices. An effective solution can be found in the advancement of high-performance supercapacitors by developing with the qualities of being integrated, elastic, and self-healable, without requiring additional film layers. Hydrogels greatly contributed to achieving this owing to their interesting properties, conductivity, and flexibility. This short review explores the recent progressions in all-in-one supercapacitors powered by hydrogels, highlighting their functional mechanisms of self-healing, ion transmission, and synchronous deformation. We discussed the potential applications in wearable electronics, medical devices, and flexible energy storage systems, focusing on design optimization and new functionalities. Furthermore, we provide insights into future research directions, guiding the exploration of novel additives and achieving high and stable performance.

Dissolved iron in alkaline media is an important topic influencing a wide array of electrochemical reactions and most notably those occurring in alkaline water electrolysers. This work compiles the study techniques and strategies that have been used in the past few years to help tackle this challenging issue. Focus is made on iron solubility in the studied medias, the importance of using a quality reference electrolyte, where and how to measure iron content in the system, and also on what is agreed and what is debated concerning the influence of dissolved iron on the hydrogen evolution reaction and oxygen evolution reaction, notably in the way these electrolyte impurities do enhance or alter the reactions kinetics.

In-situ growth of catalysts for water electrolysis has gained significant advancements recently, it involves cultivating active electrocatalysts on conductive substrates such as metal foams and carbon-based materials, the latter play a pivotal role in influencing the morphology and architecture of catalysts and offer enhanced conductivity, abundant active sites, and improved mass transport. Numerous studies have predominantly focused on evaluating specific catalyst materials within various classifications and their preparation methods, but without addressing roles of supports. This review focuses on substrate considerations, performance evaluations, and prospectives. It provides a deeper understanding of the various strategies employed for in-situ growth of electrocatalysts and emphasizes the importance of different conductive substrates with case studies on the factors that affect catalytic activity. Furthermore, the prospects and challenges towards practical applications under some challenging conditions are highlighted. This review provides valuable strategies for the further development of rational design of catalyst–substrate as an enabling electrode.

The study of single redox enzymes by electrochemistry is well-established, using both mediated and direct electron exchange between the enzyme and electrode. Moving beyond single enzymes, electrochemically driven multienzyme cascades can achieve more complex transformations, and in this review, we highlight recent advances. Electrochemical control of multiple enzymes is discussed, with examples including, electrode surface modification and engineering of the enzymes to facilitate direct electron exchange with the electrode, and new developments made by the entrapment of enzymes in a highly porous electrode called the electrochemical leaf. Examples that harness the power of direct control of the potential and the ability to monitor cascade activity as electrical current, include synthesis, deracemization, and measurement of drug binding kinetics. Redox cofactors (e.g. NADP(H)) can be electrochemically regenerated by a variety of enzymes, but non-redox cofactors are less amenable to electrochemical regeneration, and we highlight enzyme cascades for adenosine triphosphate (ATP) regeneration designed with an electrochemical step to generate the required phosphate donor. Finally, we cover approaches to model electrochemically driven cascades, which predicted local environments (e.g. pH) that are difficult to measure directly and yielded guidelines for the rational design of immobilized enzyme cascade electrodes.

The high ionic strength electrolytes stand out as promising candidates in various electrochemical applications owing to their distinct properties. These electrolytes support a variety of applications including energy devices and beyond, but involve complex interfacial structures and processes, which necessitate advanced characterization methods. Scanning probe microscopy, including atomic force microscopy and scanning tunneling microscopy, is a powerful technique with high spatial resolution and is regarded as one of the most pivotal tools for unraveling the complexities of the electrochemical interface. This review summarizes the latest advancements in surface-related scientific issues revealed by in situ scanning probe microscopic studies. The prospective applications of in situ scanning probe microscopy in the study of high ionic strength electrolytes are also briefly discussed.

Operando probing of electrochemical process and further correlation to the local structural features is a crucial route for understanding the intrinsic structure–activity relationship of electroactive materials. Scanning electrochemical cell microscopy has been proven to be a powerful and versatile tool for the in situ/operando evaluation of electrochemical activity at spatial resolution down to nanometer scale. Complementary structure characterization applied to the identical locations provides an unambiguous correlation of the intrinsic electrochemical properties to local structures. This review summarizes recent advances in this correlative approach to showcase how insightful perspectives of structure–activity relationship at the single-entity level are achieved, covering electrocatalysis, photoelectrocatalysis and energy storage. We conclude by sharing our perspective on opportunities in this field.

Electrochemical Strain Microscopy (ESM) is a technique based on Atomic Force Microscopy and provides information about local ionic processes through electro-chemo-mechanical coupling. It is employed foremost in studying battery materials, from cathodes, and anodes to solid-state electrolytes. Based on this overlap we aim to connect the electrochemistry community further with those employing ESM, by providing the current understanding of ESM, starting with a thorough introduction to the technique. In the second section, typical applications and challenges identified in recent years are reviewed while in the third chapter new approaches to overcome these issues are presented. This includes the identification of various contributions to the ESM signal, the integration of ESM as part of a multi-modal characterization approach, and importantly, how to link local ESM results to the overall cell performance in batteries. Lastly, upcoming trends and new aspects are discussed, including the application of in-situ ESM directly in an electrochemical environment.

The selective electrochemical oxidation of methane to value-added chemicals has been pursued for decades without breakthroughs and developments beyond academic research. Main setbacks encountered in virtually every report are poor methane conversion rate and selectivity. For tangible progress, research should focus on tackling CH₄ mass transport and concentration limitations. At the same time, harmonized research protocols must be developed, e.g. to define standard control experiments and key metrics. This will facilitate data comparison and accelerate electrocatalyst discovery, which so far remained challenging due to inconsistent data-reporting practices. Fundamental research on model (well-defined) electrocatalysts should also be intensified, along with in-situ spectroscopic investigations to understand the reaction mechanism and design catalysts to prevent overoxidation.