Title: Disentangling Vacancy Oxidation on Metallicity-Sorted Carbon Nanotubes Show Chinese title

Title: 分离金属型分选碳纳米管上的空位氧化

Abstract: Pristine single-walled carbon nanotubes (SWCNTs) are rather inert to O$_2$ and N$_2$, which for low doses chemisorb only on defect sites or vacancies of the SWCNTs at the ppm level. However, very low doping has a major effect on the electronic properties and conductivity of the SWCNTs. Already at low O$_2$ doses (80 L), the X-ray photoelectron spectroscopy (XPS) O 1s signal becomes saturated, indicating nearly all the SWCNT's vacancies have been oxidized. As a result, probing vacancy oxidation on SWCNTs via XPS yields spectra with rather low signal-to-noise ratios, even for metallicity-sorted SWCNTs. We show that, even under these conditions, the first principles density functional theory calculated Kohn-Sham O 1s binding energies may be used to assign the XPS O 1s spectra for oxidized vacancies on SWCNTs into its individual components. This allows one to determine the specific functional groups or bonding environments measured. We find the XPS O 1s signal is mostly due to three O-containing functional groups on SWCNT vacancies: epoxy (C$_2$$>$O), carbonyl (C$_2$$>$C$=$O), and ketene (C$=$C$=$O), as ordered by abundance. Upon oxidation of nearly all the SWCNT's vacancies, the central peak's intensity for the metallic SWCNT sample is 60\% greater than for the semiconducting SWCNT sample. This suggests a greater abundance of O-containing defect structures on the metallic SWCNT sample. For both metallic and semiconducting SWCNTs, we find O$_2$ does not contribute to the measured XPS O~1s spectra. Show Chinese abstract

Abstract: 纯净的单壁碳纳米管（SWCNTs）对O$_2$和N$_2$相当惰性，对于低剂量而言，仅在SWCNTs的缺陷位点或空位处发生化学吸附，在ppm级别。 然而，非常低的掺杂对SWCNTs的电子性质和导电性有显著影响。 即使在低O$_2$剂量（80 L）下，X射线光电子能谱（XPS）O 1s信号就会饱和，表明几乎所有的SWCNT空位都已被氧化。 因此，通过XPS探测SWCNT上的空位氧化会得到信噪比相当低的光谱，即使是对金属型进行分选的SWCNTs也是如此。 我们表明，即使在这些条件下，通过第一性原理密度泛函理论计算的Kohn-Sham O 1s结合能可用于将氧化空位的XPS O 1s光谱分解为其各个组成部分。 这使得能够确定所测量的具体功能基团或键合环境。 我们发现XPS O 1s信号主要是由于SWCNT空位上的三种含氧功能团：环氧（C$_2$$>$ O）、羰基（C$_2$$>$ C$=$O）和烯酮（C$=$C$=$O），按丰度顺序排列。 在几乎所有的SWCNT空位被氧化后，金属SWCNT样品的中心峰强度比半导体SWCNT样品高60%。 这表明金属SWCNT样品上含氧缺陷结构更丰富。 对于金属和半导体型单壁碳纳米管，我们发现$_2$不对测得的 XPS O~1s 谱产生贡献。