Shape-selected nanocrystals for in situ spectro-electrochemistry studies on structurally well defined surfaces under controlled electrolyte transport: A combined in situ ATR-FTIR/online DEMS investigation of CO electrooxidation on Pt.

Sylvain Brimaud,Zenonas Jusys,R Jürgen Behm

doi:10.3762/bjnano.5.86

Abstract

The suitability and potential of shape selected nanocrystals for in situ spectro-electrochemical and in particular spectro-electrocatalytic studies on structurally well defined electrodes under enforced and controlled electrolyte mass transport will be demonstrated, using Pt nanocrystals prepared by colloidal synthesis procedures and a flow cell set-up allowing simultaneous measurements of the Faradaic current, FTIR spectroscopy of adsorbed reaction intermediates and side products in an attenuated total reflection configuration (ATR-FTIRS) and differential electrochemical mass spectrometry (DEMS) measurements of volatile reaction products. Batches of shape-selected Pt nanocrystals with different shapes and hence different surface structures were prepared and structurally characterized by transmission electron microscopy (TEM) and electrochemical methods. The potential for in situ spectro-electrocatalytic studies is illustrated for COad oxidation on Pt nanocrystal surfaces, where we could separate contributions from two processes occurring simultaneously, oxidative COad removal and re-adsorption of (bi)sulfate anions, and reveal a distinct structure sensitivity in these processes and also in the structural implications of (bi)sulfate re-adsorption on the CO adlayer.

Highlights

Since the pioneering work of Bewick and coworkers [1,2], in situ infrared (IR) spectro-electrochemistry has been widely used to probe adsorbed species at the electrified solid/liquid interface under potential control
Employing in situ attenuated total reflection (ATR)-FTIR spectroscopy and mass spectrometry in a combined ATR-FTIR/differential electrochemical mass spectrometry (DEMS) flow cell set-up, we could demonstrate that shape-selected and structurally well characterized nanocrystals deposited on a Au film/Si substrate offer an attractive opportunity for performing spectro-electrochemical and in particular spectro–electrocatalytic measurements under enforced and well controlled electrolyte mass transport conditions on structurally well defined electrode surfaces
transmission electron microscopy (TEM), electrochemical and in situ ATR-FTIR characterization agreeingly demonstrated that the surface of the nanocrystals consists predominantly of well ordered facets with low index orientation, whose relative contribution depends on the synthesis conditions

Summary

Introduction

Since the pioneering work of Bewick and coworkers [1,2], in situ infrared (IR) spectro-electrochemistry has been widely used to probe adsorbed species at the electrified solid/liquid interface under potential control. The latter allows us to disentangle the contributions from the two processes, COad oxidation and (bi)sulfate re-adsorption, to the Faradaic current for the different surface orientations, illustrating the potential of this approach.

Results

Conclusion