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Title: Theoretical and experimental studies of hydrogen adsorption and desorption on Ir surfaces

Abstract

Here, we report adsorption and desorption of hydrogen on planar Ir(210) and faceted Ir(210), consisting of nanoscale {311} and (110) facets, by means of temperature programmed desorption (TPD) and density functional theory (DFT) in combination with the ab initio atomistic thermodynamics approach. TPD spectra show that only one H2 peak is seen from planar Ir(210) at all coverages whereas a single H2 peak is observed at around 440 K (F1) at fractional monolayer (ML) coverage and an additional H2 peak appears at around 360 K (F2) at 1 ML coverage on faceted Ir(210), implying structure sensitivity in recombination and desorption of hydrogen on faceted Ir(210) versus planar Ir(210), but no evidence is found for size effects in recombination and desorption of hydrogen on faceted Ir(210) for average facet sizes of 5-14 nm. Calculations indicate that H prefers to bind at the two-fold short-bridge sites of the Ir surfaces. In addition, we studied the stability of the Ir surfaces in the presence of hydrogen at different H coverages through surface free energy plots as a function of the chemical potential, which is also converted to a temperature scale. Moreover, the calculations revealed the origin of the two TPD peaks of H2more » from faceted Ir(210): F1 from desorption of H2 on {311} facets while F2 from desorption of H2 on (110) facets.« less

Authors:
 [1];  [1];  [2];  [2]
  1. Ulm Univ., Ulm (Germany)
  2. Rutgers, The State Univ. of New Jersey, Piscataway, NJ (United States)
Publication Date:
Research Org.:
Rutgers Univ., Piscataway, NJ (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1349425
Grant/Contract Number:  
FG02-93ER14331
Resource Type:
Accepted Manuscript
Journal Name:
Physical Chemistry Chemical Physics. PCCP (Print)
Additional Journal Information:
Journal Name: Physical Chemistry Chemical Physics. PCCP (Print); Journal Volume: 15; Journal Issue: 31; Journal ID: ISSN 1463-9076
Publisher:
Royal Society of Chemistry
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; reduction; oxygen; 1st-principles; NO; CO; reconstructions; chemistry; evolution; catalysts; model

Citation Formats

Kaghazchi, Payam, Jacob, Timo, Chen, Wenhua, and Bartynski, Robert A. Theoretical and experimental studies of hydrogen adsorption and desorption on Ir surfaces. United States: N. p., 2013. Web. doi:10.1039/c3cp51769a.
Kaghazchi, Payam, Jacob, Timo, Chen, Wenhua, & Bartynski, Robert A. Theoretical and experimental studies of hydrogen adsorption and desorption on Ir surfaces. United States. doi:10.1039/c3cp51769a.
Kaghazchi, Payam, Jacob, Timo, Chen, Wenhua, and Bartynski, Robert A. Mon . "Theoretical and experimental studies of hydrogen adsorption and desorption on Ir surfaces". United States. doi:10.1039/c3cp51769a. https://www.osti.gov/servlets/purl/1349425.
@article{osti_1349425,
title = {Theoretical and experimental studies of hydrogen adsorption and desorption on Ir surfaces},
author = {Kaghazchi, Payam and Jacob, Timo and Chen, Wenhua and Bartynski, Robert A.},
abstractNote = {Here, we report adsorption and desorption of hydrogen on planar Ir(210) and faceted Ir(210), consisting of nanoscale {311} and (110) facets, by means of temperature programmed desorption (TPD) and density functional theory (DFT) in combination with the ab initio atomistic thermodynamics approach. TPD spectra show that only one H2 peak is seen from planar Ir(210) at all coverages whereas a single H2 peak is observed at around 440 K (F1) at fractional monolayer (ML) coverage and an additional H2 peak appears at around 360 K (F2) at 1 ML coverage on faceted Ir(210), implying structure sensitivity in recombination and desorption of hydrogen on faceted Ir(210) versus planar Ir(210), but no evidence is found for size effects in recombination and desorption of hydrogen on faceted Ir(210) for average facet sizes of 5-14 nm. Calculations indicate that H prefers to bind at the two-fold short-bridge sites of the Ir surfaces. In addition, we studied the stability of the Ir surfaces in the presence of hydrogen at different H coverages through surface free energy plots as a function of the chemical potential, which is also converted to a temperature scale. Moreover, the calculations revealed the origin of the two TPD peaks of H2 from faceted Ir(210): F1 from desorption of H2 on {311} facets while F2 from desorption of H2 on (110) facets.},
doi = {10.1039/c3cp51769a},
journal = {Physical Chemistry Chemical Physics. PCCP (Print)},
number = 31,
volume = 15,
place = {United States},
year = {2013},
month = {6}
}

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