Methodology for the identification of carbonyl absorption maxima of carbon surface oxides in DRIFT spectra
Methodology for the identification of carbonyl absorption maxima of carbon surface oxides in DRIFT spectra
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DOI：
10.1016/j.cartre.2020.100020
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发表时间：
2021-04
期刊：
影响因子：
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通讯作者：
Felix Herold;Oliver Leubner;Katharina Jeschonek;C. Hess;A. Drochner;W. Qi;B. Etzold
中科院分区：
文献类型：
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作者：
Felix Herold;Oliver Leubner;Katharina Jeschonek;C. Hess;A. Drochner;W. Qi;B. Etzold
碳表面氧化物已被证明对各种应用中的高性能碳材料至关重要。漫反射红外傅里叶变换光谱是一种强大的时间分辨方法，可以在工艺条件下研究功能材料的表面。由于与有机分子相比，单个表面基团的贡献严重重叠，移动了吸收最大值，因此有意义的分析仍然具有挑战性。特别是由于未知的最大值，叠加带的去卷积受到强烈阻碍。在这项研究中，我们开发了一种基于水解，热退火或其组合的程序，它允许解开碳表面上的羧酸，酸酐和内酯的羰基吸收最大值。为了验证所提出的转换，通过程序升温脱附，X射线光电子能谱，电位滴定和Boehm滴定进行了彻底的表征。将该方法应用于聚合物衍生的参比物质，可以推导出羰基吸收最大值，其对于内酯位于1771 cm-1，对于羧酸位于1753 cm-1和1760 cm-1之间，对于羧酸酐位于1792 cm-1和1852 cm-1。这使得羰基带的去卷积，为原位时间分辨分析铺平了道路。
Carbon surface oxides have been demonstrated to be crucial for high performing carbon materials in various applications. Diffuse reflectance infrared Fourier transform spectroscopy represents a powerful time-resolved method to study the surfaces of functional materials under process conditions. Due to the severe overlap of the contributions of individual surface groups in combination with compared to organic molecules shifted absorption maxima meaningful analysis remains challenging. Especially due to the unknown maxima, deconvolution of the superimposed bands is strongly hindered. In this study, we developed a procedure based on hydrolysis, thermal annealing or a combination thereof, which allows to disentangle carbonyl absorption maxima of carboxylic acids, anhydrides and lactones on carbon surfaces. In order to verify the proposed transformations, thorough characterization by temperature programmed desorption, X-ray photoelectron spectroscopy, potentiometric titration and Boehm titration was carried out. Applying this procedure for a polymer derived reference material, the carbonyl absorption maximum could be deduced, which are positioned for lactones at 1771 cm−1, for carboxylic acids between 1753 cm−1and 1760 cm−1, and for carboxylic anhydrides at 1792 cm-1and 1852 cm-1. This allowed deconvolution of the carbonyl band, paving the way forin situtime-resolved analyses.