Bromination of double-walled carbon nanotubes (DWCNTs) was carried out using a saturated vapor of Br2 at room temperature with or without a pretreatment in bromine water. X-ray photoelectron spectroscopy revealed that ultrasound pretreatment modified the chemical state of bromine in the product. The binding energies of the Br 3d electrons in the pre-sonicated DWCNT sample were between those characteristic of the covalent C–Br bonds and the negatively charged Br2 molecules, observed when the pretreatment was not performed. Raman spectroscopy, however, clearly evidenced Br–Br vibrations in both brominated samples. Calculations of CNT–Br2 models within density functional theory were used to propose that the electronic state of a Br2 molecule depends on the adsorption site. The bromine molecules prefer to be located near edge hydroxyl groups, which acept the electron density from Br2. This increases the binding energy of Br 3d levels as compared to that for Br2 molecules in other adsorption sites.

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超声预处理对双壁碳纳米管溴化的影响

双壁碳纳米管 (DWCNT) 的溴化是在室温下使用 Br2 的饱和蒸汽在溴水中进行或不进行预处理的情况下进行的。X 射线光电子能谱显示超声预处理改变了产品中溴的化学状态。预超声处理的 DWCNT 样品中 Br 3d 电子的结合能介于共价 C-Br 键和带负电荷的 Br2 分子的那些特征之间，这是在未进行预处理时观察到的。然而，拉曼光谱清楚地证明了两种溴化样品中的 Br-Br 振动。密度泛函理论中 CNT-Br2 模型的计算被用来提出 Br2 分子的电子状态取决于吸附位点。溴分子更喜欢位于边缘羟基附近，接受来自 Br2 的电子密度。与其他吸附位点的 Br2 分子相比，这增加了 Br 3d 水平的结合能。