Atomically Resolved Anisotropic Electrochemical Shaping of Nano-electrocatalyst.

Francisco Ruiz-Zepeda,Primož Jovanovič,Matija Gatalo,Miran Gaberšček,Marjan Bele,Goran Dražić,Andraž Pavlišič,Nejc Hodnik

doi:10.1021/acs.nanolett.9b00918

Francisco Ruiz-Zepeda, Primož Jovanovič + Show 6 more

Open Access

https://doi.org/10.1021/acs.nanolett.9b00918

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Abstract

Catalytic properties of advanced functional materials are determined by their surface and near-surface atomic structure, composition, morphology, defects, compressive and tensile stresses, etc; also known as a structure–activity relationship. The catalysts structural properties are dynamically changing as they perform via complex phenomenon dependent on the reaction conditions. In turn, not just the structural features but even more importantly, catalytic characteristics of nanoparticles get altered. Definitive conclusions about these phenomena are not possible with imaging of random nanoparticles with unknown atomic structure history. Using a contemporary PtCu-alloy electrocatalyst as a model system, a unique approach allowing unprecedented insight into the morphological dynamics on the atomic-scale caused by the process of dealloying is presented. Observing the detailed structure and morphology of the same nanoparticle at different stages of electrochemical treatment reveals new insights into atomic-scale processes such as size, faceting, strain and porosity development. Furthermore, based on precise atomically resolved microscopy data, Kinetic Monte Carlo (KMC) simulations provide further feedback into the physical parameters governing electrochemically induced structural dynamics. This work introduces a unique approach toward observation and understanding of nanoparticles dynamic changes on the atomic level and paves the way for an understanding of the structure–stability relationship.

Highlights

I n the past decades, we have witnessed tremendous advances in the core performance and understanding of the structure−activity relationship of materials for potential use in electrochemical devices such as fuel cells or electrolyzers
In an effort to better understand the structure−stability relationship and its related mechanisms, new methods and techniques have been proposed and developed in electron microscopy,[11] synchrotron spectroscopy,[12−14] and different analytic tools such as the online coupling of electrochemical cells to ICP-MS.[15−17] As in regard to electron microscopy, an ideal setup would involve an in situ technique employing an appropriate electrochemical liquid cell, which could allow the observation of the solid active material at the atomic level with minimal influence of the beam with the specimen, well-known reactions and liquid electrolyte
The authors show that Co segregation and oxidation take place preferentially on {111} surface facets but not on {100} surface facets, implying that {100} surface facets may maintain the activity of disordered Pt3Co oxygen reduction reaction (ORR) catalyst

Summary

Introduction

I n the past decades, we have witnessed tremendous advances in the core performance and understanding of the structure−activity relationship of materials for potential use in electrochemical devices such as fuel cells or electrolyzers.

Results

Conclusion