Bai Ruobing, Tolman Nathan L, Peng Zhenbo, Liu Haitao
Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States.
Chemical Engineering College, Ningbo Polytechnic, Ningbo, Zhejiang 315806, P. R. China.
Langmuir. 2023 Aug 29;39(34):12159-12165. doi: 10.1021/acs.langmuir.3c01459. Epub 2023 Aug 15.
Airborne hydrocarbon contamination occurs rapidly on graphitic surfaces and negatively impact many of their material properties, yet much of the molecular details of the contamination remains unknown. We use Kelvin probe force microscopy (KPFM) to study the time evolution of the surface potential of graphite exposed to ambient. After exfoliation in air, the surface potential of graphite is not homogeneous and contains features that are absent in the topography image. In addition, the heterogeneity of the surface potential images increased in the first few days followed by a decrease at longer exposure times. These observations are strong support of slow conformation change, phase separation, and/or dynamic displacement of the adsorbed airborne contaminants.
空气中的碳氢化合物会迅速在石墨表面形成污染，并对其许多材料性能产生负面影响，但这种污染的许多分子细节仍不为人知。我们使用开尔文探针力显微镜（KPFM）来研究暴露在环境中的石墨表面电势随时间的变化。在空气中剥离后，石墨的表面电势并不均匀，且包含形貌图像中不存在的特征。此外，表面电势图像的不均匀性在最初几天增加，随后在更长的暴露时间内下降。这些观察结果有力地支持了吸附的空气传播污染物的缓慢构象变化、相分离和/或动态位移。
