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Title: Anion adsorption, CO oxidation, and oxygen reduction reaction on a Au(100) surface: The pH effect

Abstract

The effects of pH on the surface reconstruction of Au(100), on CO oxidation, and on the oxygen reduction reaction (ORR) have been studied by a combination of surface X-ray scattering (SXS), Fourier transform infrared (FTIR) spectroscopy, and rotating ring-disk electrode (RRDE) measurements. In harmony with previous SXS and scanning tunneling microscopy (STM) results, the potential-induced hexagonal (''hex'') to (1 x 1) transition occurs faster in an alkaline electrolyte than in acidic media. In alkaline solution, CO adsorption facilitates the formation of a ''hex'' phase; in acid solution, however, CO has negligible effect on the potential range of thermodynamic stability of the ''hex'' <--> (1 x 1) transition. We propose that in KOH the continuous removal of OHad in the Langmuir-Hinshelwood reaction (CO + OH) CO2 + H+ + e- may stabilize the ''hex'' phase over a much wider potential range than in CO-free solution. In acid solution, where specifically adsorbing anions cannot be displaced by CO from the Au(100) surface, CO has negligible effect on the equilibrium potential for the ''hex'' <--> (1 x 1) transition. Such a mechanism is in agreement with the pH-dependent oxidation of CO. The ORR is also affected by the pH of solution. It ismore » proposed that the pH-dependent kinetics of the ORR on Au(100) can be unraveled by finding the relationship between kinetic rates and two terms: (i) the energetic term of the Au(100)-O2- interaction determines the potential regions where the rate-determining step O2 + e = O2- occurs, and (ii) the preexponential term determines the availability of active sites for the adsorption of O2-.« less

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Director. Office of Science. Office of Basic Energy Sciences. Materials Science and Engineering Division (US)
OSTI Identifier:
827966
Report Number(s):
LBNL-55919
R&D Project: 505601; 500901; TRN: US200426%%1027
DOE Contract Number:  
AC03-76SF00098
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical
Additional Journal Information:
Journal Volume: 108; Other Information: Journal Publication Date: 2004; PBD: 29 Jul 2004
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ADSORPTION; ANIONS; AVAILABILITY; ELECTRODES; ELECTROLYTES; KINETICS; OXIDATION; OXYGEN; REMOVAL; SCANNING TUNNELING MICROSCOPY; SCATTERING; SPECTROSCOPY; STABILITY; THERMODYNAMICS

Citation Formats

Blizanac, Berislav B, Lucas, Chris A, Gallagher, Mark E, Arenz, Matthias, Ross, Philip N, and Markovic, Nenad M. Anion adsorption, CO oxidation, and oxygen reduction reaction on a Au(100) surface: The pH effect. United States: N. p., 2004. Web. doi:10.1021/jp036483l.
Blizanac, Berislav B, Lucas, Chris A, Gallagher, Mark E, Arenz, Matthias, Ross, Philip N, & Markovic, Nenad M. Anion adsorption, CO oxidation, and oxygen reduction reaction on a Au(100) surface: The pH effect. United States. https://doi.org/10.1021/jp036483l
Blizanac, Berislav B, Lucas, Chris A, Gallagher, Mark E, Arenz, Matthias, Ross, Philip N, and Markovic, Nenad M. Thu . "Anion adsorption, CO oxidation, and oxygen reduction reaction on a Au(100) surface: The pH effect". United States. https://doi.org/10.1021/jp036483l.
@article{osti_827966,
title = {Anion adsorption, CO oxidation, and oxygen reduction reaction on a Au(100) surface: The pH effect},
author = {Blizanac, Berislav B and Lucas, Chris A and Gallagher, Mark E and Arenz, Matthias and Ross, Philip N and Markovic, Nenad M},
abstractNote = {The effects of pH on the surface reconstruction of Au(100), on CO oxidation, and on the oxygen reduction reaction (ORR) have been studied by a combination of surface X-ray scattering (SXS), Fourier transform infrared (FTIR) spectroscopy, and rotating ring-disk electrode (RRDE) measurements. In harmony with previous SXS and scanning tunneling microscopy (STM) results, the potential-induced hexagonal (''hex'') to (1 x 1) transition occurs faster in an alkaline electrolyte than in acidic media. In alkaline solution, CO adsorption facilitates the formation of a ''hex'' phase; in acid solution, however, CO has negligible effect on the potential range of thermodynamic stability of the ''hex'' <--> (1 x 1) transition. We propose that in KOH the continuous removal of OHad in the Langmuir-Hinshelwood reaction (CO + OH) CO2 + H+ + e- may stabilize the ''hex'' phase over a much wider potential range than in CO-free solution. In acid solution, where specifically adsorbing anions cannot be displaced by CO from the Au(100) surface, CO has negligible effect on the equilibrium potential for the ''hex'' <--> (1 x 1) transition. Such a mechanism is in agreement with the pH-dependent oxidation of CO. The ORR is also affected by the pH of solution. It is proposed that the pH-dependent kinetics of the ORR on Au(100) can be unraveled by finding the relationship between kinetic rates and two terms: (i) the energetic term of the Au(100)-O2- interaction determines the potential regions where the rate-determining step O2 + e = O2- occurs, and (ii) the preexponential term determines the availability of active sites for the adsorption of O2-.},
doi = {10.1021/jp036483l},
url = {https://www.osti.gov/biblio/827966}, journal = {Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical},
number = ,
volume = 108,
place = {United States},
year = {2004},
month = {7}
}