Abstract
As part of the revolution in electrochemical nanoscience, there is growing interest in using electrochemistry to create nanostructured materials and to assess properties at the nanoscale. Herein, we present a platform that combines scanning electrochemical cell microscopy with ex situ scanning transmission electron microscopy to allow the ready creation of an array of nanostructures coupled with atomic-scale analysis. As an illustrative example, we explore the electrodeposition of Pt at carbon-coated transmission electron microscopy (TEM) grid supports, where in a single high-throughput experiment it is shown that Pt nanoparticle (PtNP) density increases and size polydispersity decreases with increasing overpotential (i.e., driving force). Furthermore, the coexistence of a range of nanostructures, from single atoms to aggregates of crystalline PtNPs, during the early stages of electrochemical nucleation and growth supports a nonclassical aggregative growth mechanism. Beyond this exemplary system, the presented correlative electrochemistry-microscopy approach is generally applicable to solve ubiquitous structure-function problems in electrochemical science and beyond, positioning it as a powerful platform for the rational design of functional nanomaterials.
Highlights
Over the past three decades, science has been impacted massively by the revolution in nanotechnology
Scanning electrochemical cell microscopy (SECCM)[7] is a powerful tool in single-entity studies, in which the meniscus cell protruding from an electrolyte-filled micropipet probe is used to electrochemically interrogate a single or small population of supported NPs within an ensemble.[4,8−11] For example, in a recent study, SECCM was deployed as a high-throughput screening method to probe the heterogeneous response of individual LiMn2O4 particles, revealing a diverse library of responses within a family of superficially similar singleentities.[12]
We have presented a high-throughput SECCMSTEM platform that allows structure-electrochemistry to be correlated with single-atom sensitivity
Summary
Following the electrodeposition experiments (Figure 3), the Pt “microensembles” on the CCTG substrate were imaged ex situ with HAADF-STEM, which is a powerful tool for analyzing structures arising from nucleation and growth due to its large dynamic magnification range that enables visualization of the whole droplet footprint (commensurate with the size of the micropipet probe, shown in the SI, Section S5) and down to single atoms with subnanometer resolution.[24] We demonstrate this by considering the Eapp-dependent NP distributions (i.e., size, particle count, and Pt mass) and NP morphologies. The coexistence of single atoms (Figure 5a−d) and amorphous (Figure 5a), monocrystalline (Figure 5a,b), and polycrystalline (Figure 5b− d) NPs (and aggregates of these) indicates that several early growth mechanisms occur simultaneously.[20]
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