Oxygen鈥揝ulfur Exchange and the Gas-Phase Reactivity of Cobalt Sulfide Cluster Anions with Molecular Oxygen
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- 作者：Mei-Ye Jia ; Zhixun Luo ; Sheng-Gui He ; Mao-Fa Ge
- 刊名：Journal of Physical Chemistry A
- 出版年：2014
- 出版时间：September 18, 2014
- 年：2014
- 卷：118
- 期：37
- 页码：8163-8169
- 全文大小：360K
- ISSN：1520-5215
文摘
We present here a study of gas-phase reactivity of cobalt sulfide cluster anions ComSn鈥?/sup> with molecular oxygen. Nascent ComSn鈥?/sup> clusters were prepared via a laser ablation source and reacted with oxygen in a fast flow reactor under thermal collision conditions. We chose 18O2 in place of 16O2 to avoid mass degeneration with sulfur, and a time-of-flight (TOF) mass spectrometer was used to detect the cluster distributions in the absence and presence of the reactant. It was found that oxygen鈥搒ulfur exchange occurs in the reactions for those with specific compositions (CoS)n鈥?/sup> and (CoS)nS鈥?/sup> (n = 2鈥?) according to a consistent pathway, 鈥淐omSn鈥?/sup> + 18O2 鈫?ComSn鈥?18O鈥?/sup> + S18O鈥? Typically, for 鈥淐o2S2鈥?/sup> + 18O2鈥?we have calculated the reaction coordinates by employing the density functional theory (DFT), where both the oxygen鈥搒ulfur exchange and SO molecule release are thermodynamically and kinetically favorable. It is noteworthy that the reaction with molecular oxygen (triplet ground state) needs to overcome a spin excitation as well as a large O鈥揙 activation energy. This study sheds light on the activation of molecular oxygen by cobalt sulfides on one hand and also provides insight into the regeneration mechanism of cobalt oxides from the counterpart sulfides in the presence of oxygen gas on the other hand.