de Oliveira I S S, Kagimura R, Venezuela P, Miwa R H
Departamento de Física, Universidade Federal de Lavras, C.P. 3037, 37200-000 Lavras, MG, Brazil.
Instituto de Física, Universidade Federal de Uberlândia, C.P. 593, 38400-902 Uberlândia, Brazil.
J Chem Phys. 2019 May 28;150(20):204701. doi: 10.1063/1.5093322.
We performed a theoretical investigation of single-walled carbon nanotubes (CNTs) functionalized with triazine molecules. Upon adsorption, the influence of the molecule orientation on the CNTs' electronic properties is examined by combining first-principles density functional theory calculations and simulations of X-ray Absorption Near-Edge Structure (XANES) at the C K-edge. Our calculations show that the electronic properties of functionalized CNTs can preserve the same features of pristine CNTs, for both semiconductor and metallic CNTs, depending on the orientation of the covalently bonded molecule. For that configuration, we observe a breakage of the CNT C-C bond at the molecule adsorption site. Moreover, the XANES spectra reveal that sp bonding hybridization is preserved along the CNT network. On the other hand, the electronic properties of pristine CNTs are no longer preserved for adsorbed molecule orientations resulting in intact C-C bond at the adsorption site. In this case, the XANES spectra indicate that the molecule-CNT interactions result in sp hybridization. Our findings help to elucidate whether π-conjugation is preserved in functionalized CNTs, demonstrating that calculations of XANES spectra are a powerful tool to resolve such systems.
我们对用三嗪分子功能化的单壁碳纳米管（CNT）进行了理论研究。吸附后，通过结合第一性原理密度泛函理论计算和碳K边的X射线吸收近边结构（XANES）模拟，研究了分子取向对碳纳米管电子性质的影响。我们的计算表明，对于半导体和金属碳纳米管，功能化碳纳米管的电子性质可以保留原始碳纳米管的相同特征，这取决于共价键合分子的取向。对于该构型，我们观察到在分子吸附位点处碳纳米管的C-C键断裂。此外，XANES光谱表明sp键杂化沿碳纳米管网络得以保留。另一方面，对于在吸附位点导致完整C-C键的吸附分子取向，原始碳纳米管的电子性质不再保留。在这种情况下，XANES光谱表明分子与碳纳米管的相互作用导致sp杂化。我们的研究结果有助于阐明功能化碳纳米管中π共轭是否得以保留，表明XANES光谱计算是解析此类体系的有力工具。
