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One of the grand challenges facing electrochemistry is to directly resolve the complex nature of (electro)catalyst active sites and capture real-time “movies” of reaction dynamics, i.e. “watching chemistry in action”. The need for such fundamental understanding has stimulated the development of operando/in situ methods, which have greatly enhanced our ability to identify activity descriptors of electrocatalysts and establish structure–property relationships of energy materials. This review summarizes the frontiers of operando electrochemical liquid-cell scanning transmission electron microscopy and correlative synchrotron X-ray methods, which are complementary tools to comprehensively investigate reaction dynamics across multiple spatiotemporal scales. In an effort to encourage greater adoption of advanced operando methods by the general electrochemistry community, this review points out the need to benchmark electrochemistry in confined and heterogenous liquid environment with minimal beam-induced damage. We anticipate that multimodal operando methods will become indispensable for understanding interfacial reaction mechanisms for the broad chemistry and energy materials communities.

Reversible cyclopropane formation is probed as a means of redox noninnocence in diimine/diamide chelates via reduction and complex anion formation. Competition from imine attack renders complications in the latter approach, and electrochemical measurements with calculational support provide the rationale. [ABSTRACT FROM AUTHOR]

Reversible cyclopropane formation is probed as a means of redox noninnocence in diimine/diamide chelates via reduction and complex anion formation. Competition from imine attack renders complications in the latter approach, and electrochemical measurements with calculational support provide the rationale. [ABSTRACT FROM AUTHOR]

The article provides information on a study focused on lithium-sulfur batteries, exploring the electrocatalytic mechanisms using a cobalt single-atom electrocatalyst through operando confocal Raman microscopy and x-ray absorption spectroscopy. The study reveals that Co-SAs/NC effectively accelerates lithium-sulfur reduction/oxidation reactions and transforms the stepwise mechanism of long-chain and intermediate-chain polysulfides into a concurrent pathway under electrocatalysis.

Anion exchange membrane fuel cells (AEMFCs) have successfully eliminated anode carbonate precipitation through cation immobilization with the incorporation of alkaline polymer electrolytes (APEs). However, carbonation by CO 2 in ambient air continues to induce significant AEMFC performance losses via mechanisms that remain unclear/elusive. In this multimodal investigation of AEMFC carbonation, we find that the increase in ionic resistance after carbonation accounts for only a small fraction of the cell voltage drop, especially at high current densities. Controlled anode and cathode carbonation tests indicated that the anode hydrogen oxidation reaction (HOR) was significantly impeded by carbonation. Hydrogen pump tests showed that the HOR kinetics were more than an order of magnitude lower after carbonation, thus accounting for the large decrease in the cell voltage. Further studies using the electrochemical quartz crystal microbalance (EQCM) revealed that there exists a large barrier to the rearrangement of the double layer at the Pt/ionomer interface in the hydrogen underpotential deposition (HUPD) region, which may explain the slower HOR kinetics after carbonation. These results provide fundamental insight into the unique properties of the catalyst/APE interface and suggest new directions for energy materials and technology developments.

Reversible cyclopropane formation is probed as a means of redox noninnocence in diimine/diamide chelates via reduction and complex anion formation. Competition from imine attack renders complications in the latter approach, and electrochemical measurements with calculational support provide the rationale.