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C-O bond activation and splitting behaviors of CO2 on 4H-SiC surface: a DFT study

Abstract

Conversion of CO2 into valuable chemicals can not only reduce the amount of CO2 in the atmosphere, but also realize the reuse of resources. It’s well known that C-O bond activation and splitting are critical steps in the CO2 conversion process and it's crucial to employ an appropriate catalyst. Here, the adsorption and activation behaviors of CO2 molecule on 4H-SiC surfaces were systematically investigated based on DFT calculations. Calculation results show that CO2 molecule can anchor on 4H-SiC (0001) and (0001(-)) surfaces. On 4H-SiC (0001) surface, the adsorbed CO2 molecule prefers to dissociate with an energy barrier of 0.58-0.68 eV, producing O adatom and CO molecule on the surface. Further dissociation of CO is hindered due to large energy barrier of 2.20 eV. However, if H atom is introduced, CO molecule may combine with H into a CHO group and the reation energy barrier is 1.65 eV. Moreover, CHO group tends to transform into CH group and O adatom in which reaction only a low energy barrier of 0.22 eV needs to be surmounted. For 4H-SiC (0001(-)) case, the direct C-O bond dissociation energy barrier for CO2 is only 0.42 eV while further breaking of the C-O bond in CO is energy unfavorable even with the help of H atom. So the final products is O adatom and CO chemisorbed on the 4H-SiC (0001(-)) surface. All the calculation results demonstrate that the inert CO2 molecule can be effectively activated on both the 4H-SiC (0001) and (0001(-)) surfaces and different splitting products could be obtained on the two different surfaces, implying that SiC is an applicable catalyst material for CO2 conversion with high efficiency and product selectivity.

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Supplementary files

Publication details

The article was received on 13 Jul 2018, accepted on 08 Oct 2018 and first published on 09 Oct 2018


Article type: Paper
DOI: 10.1039/C8CP04438D
Citation: Phys. Chem. Chem. Phys., 2018, Accepted Manuscript
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    C-O bond activation and splitting behaviors of CO2 on 4H-SiC surface: a DFT study

    D. D. Wang, L. Zhang, D. Han, L. Niu, X. Zhong, X. Qu, L. H. Yang, J. Zhao and H. Li, Phys. Chem. Chem. Phys., 2018, Accepted Manuscript , DOI: 10.1039/C8CP04438D

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