Guided ion-beam studies of the reactions of Con+ (n=2–20) with O2: Cobalt cluster-oxide and -dioxide bond energies

Abstract

The kinetic-energy dependence for the reactions of Co(n)+ (n=2-20) with O2 is measured as a function of kinetic energy over a range of 0 to 10 eV in a guided ion-beam tandem mass spectrometer. A variety of Co(m)+, Co(m)O+, and Co(m)O2+ (m < or = n) product ions is observed, with the dioxide cluster ions dominating the products for all larger clusters. Reaction efficiencies of Co(n)+ cations with O2 are near unity for all but the dimer. Bond dissociation energies for both cobalt cluster oxides and dioxides are derived from threshold analysis of the energy dependence of the endothermic reactions using several different methods. These values show little dependence on cluster size for clusters larger than three atoms. The trends in this thermochemistry and the stabilities of oxygenated cobalt clusters are discussed. The bond energies of Co(n)+-O for larger clusters are found to be very close to the value for desorption of atomic oxygen from bulk-phase cobalt. Rate constants for O2 chemisorption on the cationic clusters are compared with results from previous work on cationic, anionic, and neutral cobalt clusters.

Influence of Cr doping on the stability and structure of small cobalt oxide clusters

“…[19][20][21] Their stability, structures, chemical reactivities, ionization energies, dissociation energies, and magnetic properties are engaging and challenging subjects. [22][23][24][25][26][27] Triggered by the above listed examples that illustrate the effect of dopant atoms on the properties of metal oxide clusters, we set out to investigate the influence of chromium dopants on the structure and stability of cobalt oxide clusters. These clusters likely have interesting magnetic properties, since Co and Cr, both 3d transition metals, are ferromagnetic and antiferromagnetic in bulk, respectively.…”

Oxidation reactions on neutral cobalt oxideclusters: experimental and theoretical studies

“…CO 2 is formed through a structure in which the carbon atom of CO is bonded to both the Co(III) and a neighboring oxygen atom. 28 [48][49][50][51][52][53][54][55][56][57][58][59][60][61][62] For cobalt oxide clusters, electronic and geometric structures for neutral and anionic CoO n (n = 1-4) clusters have been reported by Uzunova et al, and a dissociation channel, loss of a dioxygen molecule, is suggested based on their DFT calculations. 63 In addition, Co m O n À (m = 4-20, n = 0-2) anion clusters are generated by a laser ablation source and are investigated by photoelectron spectroscopy.…”

Gas-phase perspective on the thermodynamics and kinetics of heterogeneous catalysis

“…The kinetic energy dependence of reactions of metal cluster cations with O 2 has been studied for V n 20), and Ni n + (n = 2-18). [70][71][72][73][74] Most transition metal cluster cations (as well as neutrals) react with O 2 efficiently to form a cluster dioxide, reaction (11). The reaction efficiencies approach 100% of the collision cross section and rapidly reach the hard-sphere limit, as shown for the example of V 10 + in Fig.…”