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Title: Influence of * OH adsorbates on the potentiodynamics of the CO 2 generation during the electro-oxidation of ethanol

Abstract

Direct ethanol fuel cells (DEFCs) are a promising technology for the generation of electricity via the direct conversion of ethanol into CO2, showing higher thermodynamic efficiency and volumetric energy density than hydrogen fuel cells. However, implementation of DEFCs is hampered by the low CO2 selectivity during the ethanol oxidation reaction (EOR). Comprehensive understanding of the electro-kinetics and reaction pathways of CO2 generation via CC bond-breaking is not only a fundamental question for electro-catalysis, but also a key technological challenge since practical implementation of DEFC technology is contingent on its ability to selectively oxidize ethanol into CO2 to achieve exceptional energy density through 12-electron transfer reaction. Here, we present comprehensive in situ potentiodynamics studies of CO2 generation during the EOR on Pt, Pt/SnO2 and Pt/Rh/SnO2 catalysts using a house-made electrochemical cell equipped with a CO2 microelectrode. Highly sensitive CO2 measurements enable the real time detection of the partial pressure of CO2 during linear sweep voltammetry measurements, through which electro-kinetics details of CO2 generation can be obtained. In situ CO2 measurements provide the mechanistic understanding of potentiodynamics of the EOR, particularly the influence of *OH adsorbates on CO2 generation rate and selectivity. Density functional theory (DFT) simulations of Pt, Pt/SnO2, and Pt/Rh/SnO2more » surfaces clarify reaction details over these catalysts. Our results show that at low potentials, inadequate *OH adsorbates impair the removal of reaction intermediates, and thus Pt/Rh/SnO2 exhibited the best performance toward CO2 generation, while at high potentials, Rh sites were overwhelmingly occupied (poisoned) by *OH adsorbates, and thus Pt/SnO2 exhibited the best performance toward CO2 generation.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1409561
Report Number(s):
BNL-114613-2017-JA¿¿¿
Journal ID: ISSN 0021-9517
DOE Contract Number:
SC0012704
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Catalysis; Journal Volume: 353; Journal Issue: C
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Yang, Guangxing, Namin, Lida M., Aaron Deskins, N., and Teng, Xiaowei. Influence of * OH adsorbates on the potentiodynamics of the CO 2 generation during the electro-oxidation of ethanol. United States: N. p., 2017. Web. doi:10.1016/j.jcat.2017.07.033.
Yang, Guangxing, Namin, Lida M., Aaron Deskins, N., & Teng, Xiaowei. Influence of * OH adsorbates on the potentiodynamics of the CO 2 generation during the electro-oxidation of ethanol. United States. doi:10.1016/j.jcat.2017.07.033.
Yang, Guangxing, Namin, Lida M., Aaron Deskins, N., and Teng, Xiaowei. Fri . "Influence of * OH adsorbates on the potentiodynamics of the CO 2 generation during the electro-oxidation of ethanol". United States. doi:10.1016/j.jcat.2017.07.033.
@article{osti_1409561,
title = {Influence of * OH adsorbates on the potentiodynamics of the CO 2 generation during the electro-oxidation of ethanol},
author = {Yang, Guangxing and Namin, Lida M. and Aaron Deskins, N. and Teng, Xiaowei},
abstractNote = {Direct ethanol fuel cells (DEFCs) are a promising technology for the generation of electricity via the direct conversion of ethanol into CO2, showing higher thermodynamic efficiency and volumetric energy density than hydrogen fuel cells. However, implementation of DEFCs is hampered by the low CO2 selectivity during the ethanol oxidation reaction (EOR). Comprehensive understanding of the electro-kinetics and reaction pathways of CO2 generation via CC bond-breaking is not only a fundamental question for electro-catalysis, but also a key technological challenge since practical implementation of DEFC technology is contingent on its ability to selectively oxidize ethanol into CO2 to achieve exceptional energy density through 12-electron transfer reaction. Here, we present comprehensive in situ potentiodynamics studies of CO2 generation during the EOR on Pt, Pt/SnO2 and Pt/Rh/SnO2 catalysts using a house-made electrochemical cell equipped with a CO2 microelectrode. Highly sensitive CO2 measurements enable the real time detection of the partial pressure of CO2 during linear sweep voltammetry measurements, through which electro-kinetics details of CO2 generation can be obtained. In situ CO2 measurements provide the mechanistic understanding of potentiodynamics of the EOR, particularly the influence of *OH adsorbates on CO2 generation rate and selectivity. Density functional theory (DFT) simulations of Pt, Pt/SnO2, and Pt/Rh/SnO2 surfaces clarify reaction details over these catalysts. Our results show that at low potentials, inadequate *OH adsorbates impair the removal of reaction intermediates, and thus Pt/Rh/SnO2 exhibited the best performance toward CO2 generation, while at high potentials, Rh sites were overwhelmingly occupied (poisoned) by *OH adsorbates, and thus Pt/SnO2 exhibited the best performance toward CO2 generation.},
doi = {10.1016/j.jcat.2017.07.033},
journal = {Journal of Catalysis},
number = C,
volume = 353,
place = {United States},
year = {Fri Sep 01 00:00:00 EDT 2017},
month = {Fri Sep 01 00:00:00 EDT 2017}
}