Graduate School of Engineering , Chiba University , 1-33 Yayoi , Inage , Chiba 263-8522 , Japan.
Anal Chem. 2018 Sep 18;90(18):10724-10731. doi: 10.1021/acs.analchem.8b00949. Epub 2018 Aug 29.
Edge structures of carbon materials such as zigzag and armchair edges are known to affect their chemical and electronic properties. Although infrared spectroscopy (IR) has been known to be capable of identifying such edge structures, quantitative analysis using IR spectra has been conducted using only out-of-plane spC-H bending vibration, and the estimation of the percentage of edges is still challenging. In this work, a novel two-dimensional method to quantify edge structures of carbon materials with and without pentagons was developed by analyzing both out-of-plane spC-H bending and in-plane spC-H stretching vibration. Calibration factors of spC-H on each type of edge were obtained from experimental and simulated IR spectra of various reference compounds. Using the calibration factors, the edge structures of carbonized aromatic compounds with zigzag edges such as tetracene, armchair edges such as chrysene, and zigzag-like edges such as coronene were estimated quantitatively. From tetracene carbonized at 893 K, chrysene carbonized at 933 K, and coronene carbonized at 873 K, carbon materials with 20% of zigzag edges, 38% of armchair edges, and 67% of others edges were prepared, respectively. This method can be utilized as a quantitative analysis to determine edge structures of various carbon materials prepared below 933 K at the lowest.
碳材料的边缘结构，如锯齿形和扶手椅形边缘，已知会影响它们的化学和电子性质。尽管已经知道红外光谱（IR）能够识别这种边缘结构，但使用 IR 光谱进行的定量分析仅使用了面外 spC-H 弯曲振动，并且对边缘的百分比的估计仍然具有挑战性。在这项工作中，通过分析面外 spC-H 弯曲和平面内 spC-H 伸缩振动，开发了一种新的二维方法来定量具有和不具有五边形的碳材料的边缘结构。从各种参考化合物的实验和模拟 IR 光谱中获得了每种边缘的 spC-H 的校准因子。使用校准因子，定量估计了具有锯齿形边缘的碳化芳族化合物（如四环烯）、扶手椅形边缘的化合物（如屈）和类似锯齿形边缘的化合物（如蔻烯）的边缘结构。分别从 893 K 碳化的四环烯、933 K 碳化的屈和 873 K 碳化的蔻烯中制备了具有 20%锯齿形边缘、38%扶手椅形边缘和 67%其他边缘的碳材料。这种方法可用于定量分析，以确定在 933 K 以下制备的各种碳材料的边缘结构。
