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Nanoscale Electrochemical Movies and Synchronous Topographical Mapping of Electrocatalytic Materials


Techniques in the scanning electrochemical probe microscopy (SEPM) family have shown great promise for resolving nanoscale structure-function (e.g., catalytic activity) at complex (electro)chemical interfaces, which is a long-term aspiration in (electro)materials science. In this work, we explore how a simple meniscus imaging probe, based on an easily-fabricated, single-channeled nanopipet (inner diameter ≈ 30 nm) can be deployed in the scanning electrochemical cell microscopy (SECCM) platform as a fast, versatile and robust method for the direct, synchronous electrochemical/topographical imaging of electrocatalytic materials at the nanoscale. Topographical and voltammetric data are acquired synchronously at a spatial resolution of 50 nm to construct maps that resolve particular surface features on the sub-10 nm scale and create electrochemical activity movies composed of hundreds of potential-resolved images on the minutes timescale. Using the hydrogen evolution reaction (HER) at molybdenite (MoS2) as an exemplar system, the experimental parameters critical to achieving a robust scanning protocol (e.g., approach voltage, reference potential calibration) with high resolution (e.g., hopping distance) and optimal scan times (e.g., voltammetric scan rate, approach rate etc.) are considered and discussed. Furthermore, sub-nanoentity reactivity mapping is demonstrated with glassy carbon (GC) supported single-crystalline {111}-oriented two-dimensional Au nanocrystals (AuNCs), which exhibit uniform catalytic activity at the single-entity and sub-single entity level. The approach outlined herein signposts a future in (electro)materials science in which the activity of electroactive nanomaterials can be viewed directly and related to structure through electrochemical movies, revealing active sites unambiguously.

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Publication details

The article was received on 12 Feb 2018, accepted on 19 Mar 2018 and first published on 22 Mar 2018

Article type: Paper
DOI: 10.1039/C8FD00028J
Citation: Faraday Discuss., 2018, Accepted Manuscript
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    Nanoscale Electrochemical Movies and Synchronous Topographical Mapping of Electrocatalytic Materials

    C. L. Bentley and P. R. Unwin, Faraday Discuss., 2018, Accepted Manuscript , DOI: 10.1039/C8FD00028J

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