Adsorption mechanism of the environmentally friendly insulating gas C 5 F 10 O and its main decomposition products on a Cu (1 1 1) surface

The perfluoroketone C 5 F 10 O, not only has good environmental compatibility, but also has excellent insulation properties and has the potential to replace SF 6 in medium and low voltage switchgear. This paper focuses on the compatibility of C 5 F 10 O and its main decomposition products with the copper material inside the equipment and specifically constructs several adsorption models of C 5 F 10 O and its main decomposition products on a Cu (1 1 1) surface. The adsorption mechanism was studied from a system structure, electron density distribution and density of states perspective. The results showed that C 5 F 10 O mainly adsorbed chemically on the Cu surface through carbonyl oxygen atoms. Its maximum adsorption energy is −24.48 kcal mol −1 , with electrons transferring from the copper surface to the adsorbed oxygen atom; and the adsorption energies of the main breakdown products CF 4 , C 2 F 6 , C 3 F 8 , C 3 F 6 , CF 2 O, C 2 F 4 O and CO 2 with the surface are all less than −9.56 kcal mol −1 . There is no obvious electron transfer between these decomposition gases and the copper surface, and thus, they belong to physical adsorption; while the adsorption energies of C 3 F 6 O, C 2 F 4 and CO in the top, bridge and Hcc sites are respectively −9.661 kcal mol −1 , −14.651 kcal mol −1 and −25.489 kcal mol −1 , electrons on the copper surface transfer to the oxygen atom of C 3 F 6 O and carbon atoms of C 2 F 4 and CO, forming stable chemical bonds, which belong to chemical adsorption. Through further analysis of the electron density of states, it is found that C 5 F 10 O and C 3 F 6 O bonded to the copper surface mainly by p orbitals on carbonyl oxygen atom and the pseudogaps are 3.2 eV and 2.5 eV. C 2 F 4 and CO bonded to the copper surface by sp hybrid orbitals of carbon atoms, with a pseudogap of about 4 eV. Based on the above analysis, it can be seen that C 5 F 10 O and its main decomposition products C 3 F 6 O, C 2 F 4 and CO have poor compatibility with metal copper.