title: Does Each Atom Count in the Reactivity of Vanadia Nanoclusters?
abstract: Vanadium oxide cluster anions (V2O5)nVxOy-(n = 1-31; x = 0, 1; and x + y ≤ 5) with different oxygen deficiencies (Δ = 2y-1-5x = 0, ± 1, and ±2) have been prepared by laser ablation and reacted to abstract hydrogen atoms from alkane molecules (n-butane) in a fast flow reactor. When the cluster size n is less than 25, the Δ = 1 series [(V2O5)nO-clusters] that can contain atomic oxygen radical anions (O•-) generally have much higher reactivity than the other four cluster series (Δ = -2, -1, 0, and 2), indicating that each atom counts in the hydrogen-atom abstraction (HAA) reactivity. Unexpectedly, all of the five cluster series have similar HAA reactivity when the cluster size is greater than 25. The critical dimension of vanadia particles separating the cluster behavior (each atom counts) from the bulk behavior (each atom contributes a little part) is thus about 1.6 nm (∼V50O125). The strong electron-phonon coupling of the vanadia particles has been proposed to create the O•-radicals (V5+= O2-+ heat → V4+-O•-) for the n > 25 clusters with Δ = -2, -1, 0, and 2. Such a mechanism is supported by a comparative study with the scandium system [(Sc2O3)nScxOy-(n = 1-29; x = 0, 1; and x + y ≤ 4)] for which the Δ = 1 series [(Sc2O3)nO-clusters] always have much higher HAA reactivity than the other cluster series.
authors.affiliation: Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, People's Republic of China.|University of Chinese Academy of Sciences , Beijing 100049, People's Republic of China.
authors.forename: Mei-Qi
authors.initials: MQ
authors.lastname: Zhang
authors.affiliation: Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, People's Republic of China.
authors.forename: Yan-Xia
authors.initials: YX
authors.lastname: Zhao
authors.affiliation: Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, People's Republic of China.|University of Chinese Academy of Sciences , Beijing 100049, People's Republic of China.
authors.forename: Qing-Yu
authors.initials: QY
authors.lastname: Liu
authors.affiliation: Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, People's Republic of China.
authors.forename: Xiao-Na
authors.initials: XN
authors.lastname: Li
authors.affiliation: Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, People's Republic of China.
authors.forename: Sheng-Gui
authors.identifier: 0000-0002-9919-6909
authors.initials: SG
authors.lastname: He