Progress and pitfalls in measuring the double-layer capacitance of platinum electrodes

Current Opinion in Electrochemistry, vol. 53, pp. 101727

Abstract

Despite extensive research, the double-layer structure at Pt/aqueous electrolyte interfaces (quantified by the double-layer capacitance, C dl ) remains incompletely understood as even for the model Pt(111)/HClO 4 interface, anomalous C dl trends have been reported. These trends were previously ascribed to differences in measurement techniques ( i.e. , dc methods such as cyclic voltammetry versus ac methods such as electrochemical impedance spectroscopy, EIS). However, by repeating these measurements using EIS, we clarify that these anomalous C dl trends are not measurement artefacts, but instead reflect intrinsic properties of the Pt(111)/HClO 4 interface, necessitating continued investigation. We further highlight the complexity introduced by electrosorbed H ads and/or OH ads species resulting from catalytic H 2 O dissociation, which contribute an adsorption (pseudo-)capacitance, C ads . This complicates the deconvolution of C dl from total capacitance, a challenge further exacerbated by structure-dependent adsorption between different Pt facets. Our goal is to clarify how these factors affect capacitance interpretation at Pt/aqueous electrolyte interfaces, particularly highlighting the progress and challenges in accurately extracting C dl values from prior studies.

Authors 2

1. Nicci L. Fröhlich Aachen

   Leiden University

   Affiliation as printed

   Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC Leiden, the Netherlands

2. Marc T. M. Koper Aachen

   Leiden University

   Affiliation as printed

   Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC Leiden, the Netherlands