Density functional theory study of rhodium adsorption on single-wall carbon nanotubes

Rhodium adsorption on （6, 6） single-walled carbon nanotubes （SWCNTs） was systematically investigated by density functional theory （DFT）. According to the analysis of adsorption configurations and adsorption energies, it is found that the most stable configurations are I-H1, I-H2, O-H1, O-H2 and O-B1. The adsorption energy of O-H2 is -2.29?eV, which is 0.49?eV higher than that of I-H2. This might be attributed to the graphite's winding effect, which the well-proportioned charge density on the graphite redistributes during the formation process of SWCNTs and then induces more charge to the outside of SWCNTs than the inside. Based on the partial density of states （PDOS） and Mulliken charge analysis, it is found that 5s electrons of Rh transfer to 4d orbit, while 4d electrons transfer to SWCNTs. Therefore, the Rh atom is positively charged, while the （6, 6） SWCNTs is negatively charged. Combining the PDOS calculations with the band structure results, the magnetism of Rh adsorbed outside of SWCNTs is higher than that inside SWCNTs.