The University of Southampton
University of Southampton Institutional Repository

Scanning electrochemical microscopy: using the potentiometric mode of SECM to study the mixed potential arising from two independent redox processes

Scanning electrochemical microscopy: using the potentiometric mode of SECM to study the mixed potential arising from two independent redox processes
Scanning electrochemical microscopy: using the potentiometric mode of SECM to study the mixed potential arising from two independent redox processes
This study demonstrates how the potentiometric mode of the scanning electrochemical microscope (SECM) can be used to sensitively probe and alter the mixed potential due to two independent redox processes provided that the transport of one of the species involved is controlled by diffusion. This is illustrated with the discharge of hydrogen from nanostructured Pd hydride films deposited on the SECM tip. In deareated buffered solutions the open circuit potential of the PdH in equilibrium between its ? and ? phases (OCP???) does not depend on the tip–substrate distance while in aerated conditions it is found to be controlled by hindered diffusion of oxygen. Chronopotentiometric and amperometric measurements at several tip–substrate distances reveal how the flux of oxygen toward the Pd hydride film determines its potential. Linear sweep voltammetry shows that the polarization resistance increases when the tip approaches an inert substrate. The SECM methodology also demonstrates how dissolved oxygen affects the rate of hydrogen extraction from the Pd lattice. Over a wide potential window, the highly reactive nanostructure promotes the reduction of oxygen which rapidly discharges hydrogen from the PdH. The flux of oxygen toward the tip can be adjusted via hindered diffusion. Approaching the substrate decreases the flux of oxygen, lengthens the hydrogen discharge, and shifts OCP??? negatively. The results are consistent with a mixed potential due to the rate of oxygen reduction balancing that of the hydride oxidation. The methodology is generic and applicable to other mixed potential processes in corrosion or catalysis
0003-2700
130823083458001
Serrapede, Mara
a8fab211-39d3-4d28-8804-90e7578c69c5
Denuault, Guy
5c76e69f-e04e-4be5-83c5-e729887ffd4e
Sosna, Maciej
bb06b52f-f70a-490e-a296-e3768f31cbfe
Pesce, Giovanni Luca
e1a6d917-0788-44ab-bdd4-9dffb353be78
Ball, Richard J.
349bce36-91cb-40b4-834d-98260b42f900
Serrapede, Mara
a8fab211-39d3-4d28-8804-90e7578c69c5
Denuault, Guy
5c76e69f-e04e-4be5-83c5-e729887ffd4e
Sosna, Maciej
bb06b52f-f70a-490e-a296-e3768f31cbfe
Pesce, Giovanni Luca
e1a6d917-0788-44ab-bdd4-9dffb353be78
Ball, Richard J.
349bce36-91cb-40b4-834d-98260b42f900

Serrapede, Mara, Denuault, Guy, Sosna, Maciej, Pesce, Giovanni Luca and Ball, Richard J. (2013) Scanning electrochemical microscopy: using the potentiometric mode of SECM to study the mixed potential arising from two independent redox processes. Analytical Chemistry, 85 (17), 130823083458001. (doi:10.1021/ac4017055).

Record type: Article

Abstract

This study demonstrates how the potentiometric mode of the scanning electrochemical microscope (SECM) can be used to sensitively probe and alter the mixed potential due to two independent redox processes provided that the transport of one of the species involved is controlled by diffusion. This is illustrated with the discharge of hydrogen from nanostructured Pd hydride films deposited on the SECM tip. In deareated buffered solutions the open circuit potential of the PdH in equilibrium between its ? and ? phases (OCP???) does not depend on the tip–substrate distance while in aerated conditions it is found to be controlled by hindered diffusion of oxygen. Chronopotentiometric and amperometric measurements at several tip–substrate distances reveal how the flux of oxygen toward the Pd hydride film determines its potential. Linear sweep voltammetry shows that the polarization resistance increases when the tip approaches an inert substrate. The SECM methodology also demonstrates how dissolved oxygen affects the rate of hydrogen extraction from the Pd lattice. Over a wide potential window, the highly reactive nanostructure promotes the reduction of oxygen which rapidly discharges hydrogen from the PdH. The flux of oxygen toward the tip can be adjusted via hindered diffusion. Approaching the substrate decreases the flux of oxygen, lengthens the hydrogen discharge, and shifts OCP??? negatively. The results are consistent with a mixed potential due to the rate of oxygen reduction balancing that of the hydride oxidation. The methodology is generic and applicable to other mixed potential processes in corrosion or catalysis

This record has no associated files available for download.

More information

Published date: 2013
Organisations: Electrochemistry

Identifiers

Local EPrints ID: 356127
URI: http://eprints.soton.ac.uk/id/eprint/356127
ISSN: 0003-2700
PURE UUID: 81903ae8-30f4-4a23-ad18-a46201f710be
ORCID for Guy Denuault: ORCID iD orcid.org/0000-0002-8630-9492

Catalogue record

Date deposited: 06 Sep 2013 08:15
Last modified: 15 Mar 2024 02:44

Export record

Altmetrics

Contributors

Author: Mara Serrapede
Author: Guy Denuault ORCID iD
Author: Maciej Sosna
Author: Giovanni Luca Pesce
Author: Richard J. Ball

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×