Does Each Atom Count in the Reactivity of Vanadia Nanoclusters?,Journal of the American Chemical Society

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Does Each Atom Count in the Reactivity of Vanadia Nanoclusters?
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2016-12-21 , DOI: 10.1021/jacs.6b10839
Mei-Qi Zhang _{1,

2} , Yan-Xia Zhao ₁ , Qing-Yu Liu _{1,

2} , Xiao-Na Li ₁ , Sheng-Gui He ₁

Affiliation

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.

中文翻译：

每个原子在 Vanadia 纳米团簇的反应性中都算数吗？

氧化钒簇阴离子 (V2O5)nVxOy- (n = 1-31; x = 0, 1; and x + y ≤ 5) 具有不同的氧缺乏 (Δ = 2y-1-5x = 0, ± 1, and ±2 ) 已通过激光烧蚀制备，并在快速流动反应器中反应以从烷烃分子（正丁烷）中提取氢原子。当簇大小n小于25时，可以含有原子氧自由基阴离子(O•-)的Δ=1系列[(V2O5)nO-簇]通常比其他四个簇系列具有更高的反应活性(Δ=- 2、-1、0 和 2)，表明每个原子都计入氢原子提取 (HAA) 反应性。出乎意料的是，当簇大小大于 25 时，所有五个簇系列都具有相似的 HAA 反应性。因此，将团簇行为（每个原子计数）与体行为（每个原子贡献一小部分）分开的钒粒子的临界尺寸约为 1.6 nm（~V50O125）。钒粒子的强电子-声子耦合已被提议为 n > 25 个团簇产生 O•- 自由基（V5+ = O2-+ 热 → V4+-O•-），其中 Δ = -2, -1, 0 , 和 2. 这种机制得到与钪系统 [(Sc2O3)nScxOy- (n = 1-29; x = 0, 1; and x + y ≤ 4)] 的比较研究的支持，其中 Δ = 1系列 [(Sc2O3)nO-簇] 总是比其他簇系列具有更高的 HAA 反应性。

更新日期：2016-12-21

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