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Activated hydrogen chemisorption on Ru-Cu/SiO/sub 2/ bimetallic substrates

Journal Article · · J. Phys. Chem.; (United States)
DOI:https://doi.org/10.1021/j100325a029· OSTI ID:6084154
Hydrogen adsorption-desorption on Ru-Cu bimetallic particles supported on SiO/sub 2/ and on Cu films deposited on Ru(0001) was studied by temperature-programmed desorption (TPD) in ultrahigh vacuum. When H/sub 2/ was adsorbed on Ru-Cu/SiO/sub 2/ at elevated temperatures, subsequent TPD showed extensive high-temperature desorption of H/sub 2/. This effect was absent for Ru/SiO/sub 2/ and for Cu/SiO/sub 2/. Two H/sub 2/ peaks appeared in TPD when Ru-Cu/SiO/sub 2/ was dosed with H/sub 2/ at 423 K and cooled in H/sub 2/ to 300 K. The low-temperature peak was exchanged readily with D upon exposure to D/sub 2/ at 300 K. This peak was also vulnerable to displacement by exposure to CO at 300 K. The high-temperature peak did not exchange with D/sub 2/ and was not displaced by CO exposure. On Cu films vapor-deposited on Ru(0001), no activated chemisorption during low-pressure dosing was detectable for submonolayer and multilayer coverages of Cu. The results for hydrogen on Ru-Cu/SiO/sub 2/ are interpreted in terms of a model involving the activated migration of H(a) into the Cu-covered Ru particles, particularly along the interfaces between the two metals. TPD of CO from Ru-Cu/SiO/sub 2/, Ru/SiO/sub 2/, and Cu/SiO/sub 2/ showed no activated adsorption.
Research Organization:
Univ. of Texas, Austin (USA)
OSTI ID:
6084154
Journal Information:
J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 92:14; ISSN JPCHA
Country of Publication:
United States
Language:
English