Catalytic Oxidation of Carbon Monoxide by Gas Phase Atomic Clusters

Oxidation of carbon monoxide (CO) into CO2 is a major solution to removal of CO in air purification and this oxidation process also serves as a prototypical reaction in heterogeneous catalysis. Atomic clusters are ideal models of active sites in condensed phase systems and the elementary and catalytic oxidations of CO by gas phase metal clusters are being actively studied. We have recently studied the catalytic CO oxidation by O2 mediated with hetero-nuclear metal oxide clusters (HMOCs) using state-of-the-art mass spectrometry and quantum chemistry calculations. The HMOCs can be considered as ideal models for active sites on mixed or oxide supported catalysts at a strictly molecular level. Both charged and neutral metal oxide cluster systems were studied. A concept of electronegativity-ladder effect was proposed to account for the enhanced reactivity of noble metal (NM) doped HMOCs. This concept was successfully extended in the design of NM-free HMOCs in catalytic CO oxidation by O2. A clear picture on the reactivity of molecular oxygen species, superoxide (O2−) and peroxide (O22−), in CO oxidation was obtained. The O2− and O22− species have to be dissociated into atomic oxygen species, which can then oxidize CO directly.References[1] Z.-Y. Li, Z. Yuan, X.-N. Li, Y.-X. Zhao, S.-G. He, J. Am. Chem. Soc. 2014, 136, 14307-14313.[2] X.-N. Li, Z. Yuan, J.-H. Meng, Z.-Y. Li, S.-G. He, J. Phys. Chem. C 2015, 119, 15414-15420. [3] L.-N. Wang, X.-N. Li, L.-X. Jiang, B. Yang, Q.-Y. Liu, H.-G. Xu, W.-J. Zheng, S.-G.He, Angew. Chem. 2018, 57, 3349-3353.[4] X.-P. Zou, L.-N. Wang, X.-N. Li, Q.-Y. Liu, Y.-X. Zhao, T.-M. Ma, S.-G. He, Angew. Chem. 2018, 57, 10989-10993.[5] X.-N. Li, L.-N. Wang, L.-H. Mou, S.-G. He, J. Phys. Chem. A 2019, in press, DOI:10.1021/acs.jpca.9b05185.