TY - JOUR
T1 - Low-temperature activation of molecular oxygen by gold clusters
T2 - A stoichiometric process correlated to electron affinity
AU - Salisbury, B. E.
AU - Wallace, W. T.
AU - Whetten, R. L.
N1 - Funding Information:
This research has benefited from stimulating discussions with D.M. Cox, M.M. Kappes, M. Haruta, U. Heiz, U. Landman, and H. Hakkinen; W.A. deHeer’s assistance with the electrostatic model, Eq. (8) ; technical advice from F.E. Livingston; and funding provided by the US National Science Foundation.
PY - 2000/12/1
Y1 - 2000/12/1
N2 - The adsorption-desorption equilibria of di-Oxygen (O2) on gold cluster anions (Au(N)/-, N = 2-22) have been measured in the high-Pressure limit by pulsed flow-Reactor methods at ambient temperature. Only certain clusters (N = 2, 4, 6, 8, 10, 12, 14, 18, 20) exhibit measurable adsorption, and for most of these the reaction can be driven to completion (>90% conversion to Au(N)O2/-). In no case could secondary adsorption be detected, i.e. a 1:1 reaction stoichiometry is strictly obeyed. The size (N) variation in the adsorption free energies is correlated with the known electron affinities of the gold clusters. Taken with the positive electron affinity of O2, these results suggest that O2 acts as a single-electron acceptor, yielding adsorbed superoxide (O2/-), while the gold cluster strives to pair electrons (or close electron shells). This species could serve as an activated form for low-Temperature oxygen-Atom transfer reactions catalyzed by supported gold clusters, wherein the activation of molecular oxygen is regarded as a crucial step. (C) 2000 Elsevier Science B.V.
AB - The adsorption-desorption equilibria of di-Oxygen (O2) on gold cluster anions (Au(N)/-, N = 2-22) have been measured in the high-Pressure limit by pulsed flow-Reactor methods at ambient temperature. Only certain clusters (N = 2, 4, 6, 8, 10, 12, 14, 18, 20) exhibit measurable adsorption, and for most of these the reaction can be driven to completion (>90% conversion to Au(N)O2/-). In no case could secondary adsorption be detected, i.e. a 1:1 reaction stoichiometry is strictly obeyed. The size (N) variation in the adsorption free energies is correlated with the known electron affinities of the gold clusters. Taken with the positive electron affinity of O2, these results suggest that O2 acts as a single-electron acceptor, yielding adsorbed superoxide (O2/-), while the gold cluster strives to pair electrons (or close electron shells). This species could serve as an activated form for low-Temperature oxygen-Atom transfer reactions catalyzed by supported gold clusters, wherein the activation of molecular oxygen is regarded as a crucial step. (C) 2000 Elsevier Science B.V.
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U2 - 10.1016/S0301-0104(00)00272-X
DO - 10.1016/S0301-0104(00)00272-X
M3 - Article
AN - SCOPUS:0034548053
SN - 0301-0104
VL - 262
SP - 131
EP - 141
JO - Chemical Physics
JF - Chemical Physics
IS - 1
ER -