DFT study of the coverage-dependent chemisorption of molecular H2 on neutral cobalt dimers
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- 作者：Constantinos D. Zeinalipour-Yazdi c.zeinalipour-yazdi@ucl.ac.uk
- 刊名：Surface Science
- 出版年：2017
- 出版时间：February 2017
- 年：2017
- 卷：656
- 期：Complete
- 页码：54-59
- 全文大小：622 K
- 卷排序：656
文摘
We have studied the coverage-dependent chemisorption of H2 on neutral cobalt dimers and found at θ < 0.4 the chemisorption is dissociative without a precursor-mediated physisorbed state and at 0.4 < θ < 1 it is both molecular and dissociative with a ratio of 6:1. During H2 chemisorption which is entirely side-on there is a very large quenching of the magnetic moment Δμ = 4.9 μB and a linear weakening of the metal-metal bond strength, given by calculated oscillator frequencies. An approximate equation is derived that can be implemented in kinetic models to take account of the coverage-dependent decrease of the adsorption energy of H2 on cobalt clusters. We show that sub-nanometer cobalt clusters when exposed to H2 have strong coverage-dependent properties useful for the development of very sensitive H2-trace gas sensors in the sub-ppm range.