title: Size-dependent dissociation of carbon monoxide on cobalt nanoparticles.
abstract: In situ soft X-ray absorption spectroscopy (XAS) was employed to study the adsorption and dissociation of carbon monoxide molecules on cobalt nanoparticles with sizes ranging from 4 to 15 nm. The majority of CO molecules adsorb molecularly on the surface of the nanoparticles, but some undergo dissociative adsorption, leading to oxide species on the surface of the nanoparticles. We found that the tendency of CO to undergo dissociation depends critically on the size of the Co nanoparticles. Indeed, CO molecules dissociate much more efficiently on the larger nanoparticles (15 nm) than on the smaller particles (4 nm). We further observed a strong increase in the dissociation rate of adsorbed CO upon exposure to hydrogen, clearly demonstrating that the CO dissociation on cobalt nanoparticles is assisted by hydrogen. Our results suggest that the ability of cobalt nanoparticles to dissociate hydrogen is the main parameter determining the reactivity of cobalt nanoparticles in Fischer-Tropsch synthesis.
authors: Material Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA.
authors: Anders
authors: A
authors: Tuxen
authors: Sophie
authors: S
authors: Carenco
authors: Mahati
authors: M
authors: Chintapalli
authors: Cheng-Hao
authors: CH
authors: Chuang
authors: Carlos
authors: C
authors: Escudero
authors: Elzbieta
authors: E
authors: Pach
authors: Peng
authors: P
authors: Jiang
authors: Ferenc
authors: F
authors: Borondics
authors: Brandon
authors: B
authors: Beberwyck
authors: A Paul
authors: AP
authors: Alivisatos
authors: Geoff
authors: G
authors: Thornton
authors: Way-Faung
authors: WF
authors: Pong
authors: Jinghua
authors: J
authors: Guo
authors: Ruben
authors: R
authors: Perez
authors: Flemming
authors: F
authors: Besenbacher
authors: Miquel
authors: M
authors: Salmeron
mesh_terms: D000327:Adsorption; D002248:Carbon Monoxide / Q000737:chemistry*; D003035:Cobalt / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D013499:Surface Properties
chemical_list: D003035:Cobalt; D002248:Carbon Monoxide