Real-Time Characterization of the Fine Structure and Dynamics of an Electrical Double Layer at Electrode–Electrolyte Interfaces

Abstract

The chemisorption of an electrolyte species on electrode surfaces is ubiquitous and affects the dynamics and mechanism of various electrochemical reactions. Understanding of the chemical structure and property of the resulting electrical double layer is vital but limited. Herein, we operando probed the electrochemical interface between a gold electrode surface and a common electrolyte, phosphate buffer, using our newly developed in situ liquid secondary ion mass spectrometry. We surprisingly found that, on the positively charged gold electrode surface, sodium cations were anchored in the Stern layer in a partially dehydrated form by a formation of compact ion pairs with the accumulated phosphate anions. The resulting strong adsorption phase was further revealed to retard the electro-oxidation reaction of ascorbate. This finding addressed one major gap in the fundamental science of electrode–electrolyte interfaces, namely, where and how cations reside in the double layer to impose effects on electrochemical reactions, providing insights into the engineering of better electrochemical systems.

ToF-SIMS characterization of surface chemical evolution on electrode surfaces educed by electrochemical activation

“…Therefore, possibly the surface adsorbed Cl in the trace level also played a positive role in the activation mechanism. Furthermore real-time probing of the dynamic electrochemical processes by using newly developed in situ and operando SIMS 19,34–36 is being undertaken in our laboratory to verify such a proposed role.…”

“…Therefore, possibly the surface adsorbed Cl in the trace level also played a positive role in the activation mechanism. Furthermore real-time probing of the dynamic electrochemical processes by using newly developed in situ and operando SIMS 19,[34][35][36] is being undertaken in our laboratory to verify such a proposed role. Moreover, it is worth pointing out that when using Pt as the counter electrode in acidic electrolytes, special attention should be paid to checking whether corrosion of the Pt electrode to Pt ions and further deposition of trace Pt adatoms on the working electrode surface occur as trace platinum might serve as catalytically active sites.…”

“…Furthermore, being attributed to the above merits and the short response time (10-200 ms), ToF-SIMS has been successfully interfaced with electrochemistry as a recently developed liquid SIMS technique to in situ and real-time probe dynamic electrode-electrolyte interfaces. 19,[34][35][36] Tracking the dynamic electrochemical interface under operando electrochemical conditions would provide a deeper understanding on how exactly the electrode surface chemical compositions were evolved during activation and how the altered electrode surface chemistry impacted the structure of the electrochemical double layer and charge transfer reactions. These investigations are being undertaken in our laboratory.…”

Advances in cutting‐edge electrode engineering toward CO2 electrolysis at high current density and selectivity: A mini‐review

“…During the electrochemical reactions, the electrode-electrolyte interface has been recognized as the exact place for the happening of the electrochemical reactions. The interface properties, such as the electrical double layer structure, and charging state of the electrode, as well as the absorbed ions, would impose significant effects on the electrochemical reaction processes [76,77] Recently, strategies have been developed to tune the interplay between the electrolyte cations and the electrode surfactant additives to favor the electrode reactivity and selectivity in CO 2 RR.…”

Molecular Mechanisms of Ph-Tunable Stability and Surface Coverage of Polypeptide Films

“…The structure and dynamics of the EDL are very complex, and therefore, despite over a century of study, significant advances in the field are still made, especially relating to the dynamic nature of the interfacial region, i.e. charging dynamics, non-local charge transfer [62] and phase separation (see recent review [63]). Atomistic detail molecular dynamics with localized charge is a versatile tool used to study the structure of the EDL, especially in regard to polyelectrolyte adsorption, because conventional mean-field models are not able to accurately predict the perturbation caused by the macromolecule on the substrate [64][65][66][67][68].…”