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Silicon clathrates have attracted interest as potential anodes for lithium‐ion batteries with unique framework structures. However, very little is known about the surface reactivity and solid electrolyte interphase (SEI) properties of clathrates. In this study, operando scanning electrochemical microscopy (SECM) is used to investigate the effect of pre‐treatment on the formation dynamics and intrinsic properties of the SEI in electrodes prepared from type I Ba8Al16Si30 silicon clathrates. Although X‐ray photoelectron spectroscopy (XPS) analysis does not reveal large changes in SEI composition, it is found through SECM measurements that ball‐milling combined with chemical acid/base etching of the clathrates lead to a more stable and rapidly formed SEI as compared to purely ball‐milled samples, resulting in enhanced coulombic efficiency. [ABSTRACT FROM AUTHOR]

Cu-based catalysts have shown structural instability during the electrochemical CO 2 reduction reaction (CO 2 RR). However, studies on monometallic Cu catalysts do not allow a nuanced differentiation between the contribution of the applied potential and the local concentration of CO as the reaction intermediate since both are inevitably linked. We first use bimetallic Ag-core/porous Cu-shell nanoparticles, which utilise nanoconfinement to generate high local CO concentrations at the Ag core at potentials at which the Cu shell is still inactive for the CO 2 RR. Using operando liquid cell TEM in combination with ex situ TEM, we can unequivocally confirm that the local CO concentration is the main source for the Cu instability. The local CO concentration is then modulated by replacing the Ag-core with a Pd-core which further confirms the role of high local CO concentrations. Product quantification during CO 2 RR reveals an inherent trade-off between stability, selectivity and activity in both systems., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

A universal nano-capillary based method for sample deposition on the silicon nitride membrane of liquid-cell transmission electron microscopy (LCTEM) chips is demonstrated. It is applicable to all substances which can be dispersed in a solvent and are suitable for drop casting, including catalysts, biological samples, and polymers. Most importantly, this method overcomes limitations concerning sample immobilization due to the fragility of the ultra-thin silicon nitride membrane required for electron transmission. Thus, a straightforward way is presented to widen the research area of LCTEM to encompass any sample which can be externally deposited beforehand. Using this method, Ni x B nanoparticles are deposited on the μm-scale working electrode of the LCTEM chip and in situ observation of single catalyst particles during ethanol oxidation is for the first time successfully monitored by means of TEM movies., (© 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.)

"Single entity" measurements are central for an improved understanding of the function of nanoparticle-based electrocatalysts without interference arising from mass transfer limitations and local changes of educt concentration or the pH value. We report a scanning electrochemical cell microscopy (SECCM) investigation of zeolitic imidazolate framework (ZIF-67)-derived Co-N-doped C composite particles with respect to the oxygen evolution reaction (OER). Surmounting the surface wetting issues as well as the potential drift through the use of a non-interfering Os complex as free-diffusing internal redox potential standard, SECCM could be successfully applied in alkaline media. SECCM mapping reveals activity differences relative to the number of particles in the wetted area of the droplet landing zone. The turnover frequency (TOF) is 0.25 to 1.5 s -1 at potentials between 1.7 and 1.8 V vs. RHE, respectively, based on the number of Co atoms in each particle. Consistent values at locations with varying number of particles demonstrates OER performance devoid of macroscopic film effects., (© 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.)

Local ion activity changes in close proximity to the surface of an oxygen depolarized cathode (ODC) were measured by scanning electrochemical microscopy (SECM). While the operating ODC produces OH - ions and consumes O 2 and H 2 O through the electrocatalytic oxygen reduction reaction (ORR), local changes in the activity of OH - ions and H 2 O are detected by means of a positioned Pt microelectrode serving as an SECM tip. Sensing at the Pt tip is based on the pH-dependent reduction of PtO and obviates the need for prior electrode modification steps. It can be used to evaluate the coordination numbers of OH - ions and H 2 O, and the method was exploited as a novel approach of catalyst activity assessment. We show that the electrochemical reaction on highly active catalysts can have a drastic influence on the reaction environment., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

In order to design more powerful electrocatalysts, developing our understanding of the role of the surface structure and composition of widely abundant bulk materials is crucial. This is particularly true in the search for alternative hydrogen evolution reaction (HER) catalysts to replace platinum. We report scanning electrochemical cell microscopy (SECCM) measurements of the (111)-crystal planes of Fe 4.5 Ni 4.5 S 8 , a highly active HER catalyst. In combination with structural characterization methods, we show that this technique can reveal differences in activity arising from even the slightest compositional changes. By probing electrochemical properties at the nanoscale, in conjunction with complementary structural information, novel design principles are revealed for application to rational material synthesis., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)