TY - JOUR
T1 - Electrochemical Surface Stress Development during CO and NO Oxidation on Pt
AU - Ha, Yeyoung
AU - Zeng, Zhenhua
AU - Cohen, Yair
AU - Greeley, Jeffrey
AU - Gewirth, Andrew A.
N1 - Funding Information:
ACKNOWLEDGMENTS This work was supported by the NSF (Grant CHE-1309731), which is gratefully acknowledged. J.G. acknowledges support from an Early Career Award from the Department of Energy, Office of Science, Office of Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division.
Publisher Copyright:
© 2016 American Chemical Society.
PY - 2016/4/28
Y1 - 2016/4/28
N2 - The adsorbate-induced surface stress during the electrochemical oxidation of CO and NO on Pt is studied with in situ surface stress measurements and density functional theory (DFT) calculations. The changes in the surface stress response, Δstress, demonstrate the interplay between the adsorbed species during the oxidation process, which is determined by the coverage and the nature of the adsorbates. The oxidation of adsorbed CO, COads, shows a nonlinear surface stress response in both acidic and alkaline electrolytes, with the greatest tensile Δstress observed in the beginning of the oxidation where the CO coverage is the highest. Once a significant amount of CO is removed, OH starts to populate the surface and the Δstress becomes compressive. This surface stress development profile - the nonlinear stress development at high COads coverages and the inflection point due to coadsorption of CO and OH - is further interrogated by DFT calculations. While a tensile to compressive switch in Δstress is observed during CO oxidation, the oxidation of another strongly bound diatomic adsorbate, NOads, shows a continuous compressive Δstress. DFT calculations show that this behavior is attributed to the adsorption of the oxidation product, NO3-, which induces a similar magnitude of compressive Δstress compared to that of NOads. Hence, the compressive Δstress from the oxide and hydroxide on the surface governs the surface stress response.
AB - The adsorbate-induced surface stress during the electrochemical oxidation of CO and NO on Pt is studied with in situ surface stress measurements and density functional theory (DFT) calculations. The changes in the surface stress response, Δstress, demonstrate the interplay between the adsorbed species during the oxidation process, which is determined by the coverage and the nature of the adsorbates. The oxidation of adsorbed CO, COads, shows a nonlinear surface stress response in both acidic and alkaline electrolytes, with the greatest tensile Δstress observed in the beginning of the oxidation where the CO coverage is the highest. Once a significant amount of CO is removed, OH starts to populate the surface and the Δstress becomes compressive. This surface stress development profile - the nonlinear stress development at high COads coverages and the inflection point due to coadsorption of CO and OH - is further interrogated by DFT calculations. While a tensile to compressive switch in Δstress is observed during CO oxidation, the oxidation of another strongly bound diatomic adsorbate, NOads, shows a continuous compressive Δstress. DFT calculations show that this behavior is attributed to the adsorption of the oxidation product, NO3-, which induces a similar magnitude of compressive Δstress compared to that of NOads. Hence, the compressive Δstress from the oxide and hydroxide on the surface governs the surface stress response.
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U2 - 10.1021/acs.jpcc.6b00697
DO - 10.1021/acs.jpcc.6b00697
M3 - Article
AN - SCOPUS:84966393642
SN - 1932-7447
VL - 120
SP - 8674
EP - 8683
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
IS - 16
ER -