TY - JOUR
T1 - Adsorption of nitrogen dioxide and nitric oxide on Pd(lll)
AU - Wickham, D. T.
AU - Banse, Barbara A.
AU - Koel, Bruce E.
N1 - Funding Information:
This work was performed at the University of Colorado at Boulder. Acknowledgment is made to the Donors of the Petroleum Research Fund, administered by the American Chemical Society, for partial support of this work. Support is also acknowledged from the National Science Foundation. The authors thank Dr. Michael Bartram for a careful reading of this manuscript and helpful suggestions concerning this work. B.A.B. gratefully acknowledges the American Association of University Women for providing an American Fellowship.
PY - 1991/2/2
Y1 - 1991/2/2
N2 - The adsorption of NO2 on Pd(111) was studied by using HREELS and TPD. NO2 adsorbs molecularly at 110 K in a μ-N,O nitrito bonding geometry. The assignment of this bonding geometry is made by comparison of the vibrational data obtained in this study with IR measurements of the NO2 symmetric and asymmetric stretching frequencies of a bridge-bonded nitro palladium complex. Chemisorbed NO2 dissociates upon heating to 180 K (at low coverages) into NO(a) and O(a). Below θNO2 = 0.25 ML, NO2 desorption is not detected; NO2 adsorption is irreversible. Above θNO2 = 0.25 ML, reversible NO2 adsorption occurs with adsorptio energies of 14 and 16 kcal mol-1 as determined by desorption activation energies. NO adsorption on Pd(111) was also studied by HREELS and TPD, in order to further understand NO2 dissociation. The NO TPD data agree well with other studies of NO on Pd(111) with desorption activation energies of 38, 21, and 20 kcal mol-1. For saturation coverages of NO at 100 K, two NO species are observed with N-O stretching modes at 1575 and 1735 cm-1. These species are assigned as NO bonded at bridge and atop sites, respectively. We also note the lack of measureable adsorption of N2O on Pd(111) at 100 K.
AB - The adsorption of NO2 on Pd(111) was studied by using HREELS and TPD. NO2 adsorbs molecularly at 110 K in a μ-N,O nitrito bonding geometry. The assignment of this bonding geometry is made by comparison of the vibrational data obtained in this study with IR measurements of the NO2 symmetric and asymmetric stretching frequencies of a bridge-bonded nitro palladium complex. Chemisorbed NO2 dissociates upon heating to 180 K (at low coverages) into NO(a) and O(a). Below θNO2 = 0.25 ML, NO2 desorption is not detected; NO2 adsorption is irreversible. Above θNO2 = 0.25 ML, reversible NO2 adsorption occurs with adsorptio energies of 14 and 16 kcal mol-1 as determined by desorption activation energies. NO adsorption on Pd(111) was also studied by HREELS and TPD, in order to further understand NO2 dissociation. The NO TPD data agree well with other studies of NO on Pd(111) with desorption activation energies of 38, 21, and 20 kcal mol-1. For saturation coverages of NO at 100 K, two NO species are observed with N-O stretching modes at 1575 and 1735 cm-1. These species are assigned as NO bonded at bridge and atop sites, respectively. We also note the lack of measureable adsorption of N2O on Pd(111) at 100 K.
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U2 - 10.1016/0039-6028(91)90347-U
DO - 10.1016/0039-6028(91)90347-U
M3 - Article
AN - SCOPUS:0026412632
SN - 0039-6028
VL - 243
SP - 83
EP - 95
JO - Surface Science
JF - Surface Science
IS - 1-3
ER -