X射线光电子能谱研究活性碳纤维表面结构

STUDIES OF ACTIVATED CARBON FIBERS’SURFACE STRUCTURE BY MEANS OF X-RAY PHOTOELECTRON SPECTROSCOPY

研制了各种不同结构的活性碳纤维。并用 X 射线光电子能谱对元素组成、相对含量、表面官能团类型以及原料、制备工艺的关系进行了全面的研究。用曲线拟合分峰技术对谱峰进行了数学处理。结果表明,C 和 O 是活性碳纤维的基本元素。采用不同原料和制备工艺,活性碳纤维表面还含有少量的 N、P、Ca 等杂原子。纤维表面碳大部分为类石墨碳,C—H是活性碳纤维一种不可忽略的基团。氧元素主要与碳生成表面含氧基团如 C—OH、C=O、C(?)及酯等。C—OH 与基体碳有一定程度的共轭。表面的氮主要以胺基或亚胺基形式存在。磷的结合态有氧化磷以及各种磷酸盐。未经活化的碳纤维,含氧官能团的含量及总含量不比相应活性碳纤维低,个别样品还高。活化过程的脱羧反应是导致活性碳纤维生成高比表面积的根本原因,提高活化温度或增加活化剂浓度时,活性碳纤维表面含氧量反而下降。

The activated carbon fibers with different structures were prepared,and bymeans of x-ray photoelectron spectroscopy,the compositions of elements.relative contents and the types of surface groups as well as the relationship between materialand manufacturing process were studied all-sidedlly.By using curve fittingmethod,the spectra peak was measured mathematically.The results show thatcarbon and oxygen are two basic elements in ACF.According to different materialsand preparing conditions used,ACF may contain a small amount of heteroatoms suchas nitrogen,phosphorus,calcium etc.Most of carbon atoms on the fiber are in theform of praphite-like carbon.It should be noted that C—H group is one of themost important groups in ACF.Oxygen mainly reacts with carbon so as to formsurface oxygen-containing groups such as C—OH,C—O,COOH and ester etc.Thegroup C—OH can conjugate with carbon framework in some extent.Nitrogen atomsare mainly in the form of amine or imine,and phosphorus is mainly in the form ofphosphorous oxide and phophate.The relative carbon fibers unactivated also existsurface oxygen-containing groups which are analogous to ACF,and the amount ofthe groups on CF is not lower than that on ACF,but even higher for a few samples.The decarboxylation reaction in activation is the main reason which makes ACFobtain high specific surface area.With the increase of activation temperature oractivator concentration,the amount of surface oxygen-containing group decreases.