In-operando surface-sensitive probing of electrochemical reactions on nanoparticle electrocatalysts: Spectroscopic characterization of reaction intermediates and elementary steps of oxygen reduction reaction on Pt

In this paper we present an in-operando spectroscopic study of the reaction intermediates involved in ORR on electrified Pt nanoparticle electrocatalysts. To accomplish this, we have synthesized Ag-Pt core-shell nanoparticles, that contain a thin shell of Pt (similar to 1 nm) uniformly deposited on a larger Ag core (similar to 60 nm). We show that these nanostructures are ideal platforms for in-operando Plasmon Enhanced Raman Spectroscopy (PERS) of ORR on Pt. We combined these PERS studies with DFT calculations to assign the measured vibrational spectra to relevant surface intermediates as a function of electrocatalyst potential. These vibrational assignments were further verified and validated by performing PERS measurements using de-oxygenated and heavy oxygen (O-2-18) saturated electrolyte. These studies allowed us to identity the presence of critical reaction intermediates (OH, O-2, OOH, and H2O) as the function of operating voltage on the Pt surface and derive voltage-dependent elementary step mechanisms of the reaction. (C) 2021 Elsevier Inc. All rights reserved.

Automated summary

This study utilized Ag-Pt core-shell nanoparticle structures, combined with in-operando Plasmon Enhanced Raman Spectroscopy and Density Functional Theory calculations, to successfully investigate the reaction intermediates generated on Pt electrocatalysts during oxygen reduction reactions, providing important insights for identifying key intermediates and deriving reaction mechanisms.