Pentagons and Heptagons on Edges of Graphene Nanoflakes Analyzed by X‑ray Photoelectron and Raman Spectroscopy

Identifying pentagons and heptagons
in graphene nanoflake (GNF)
structures at the atomic scale is important to completely understand
the chemical and physical properties of these materials. Herein, we
used X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy
to analyze the spectral features of GNFs according to the position
of pentagons and heptagons introduced onto their zigzag and armchair
edges. The XPS peak maxima were shifted to higher binding energies
by introducing the pentagons or heptagons on armchair rather than
zigzag edges, and the structures could be distinguished depending
on the positions of the introduced pentagons or heptagons. Raman spectroscopic
analyses also revealed that the position of edges with introduced
pentagons or heptagons could also be identified using Raman spectroscopy,
with characteristic bands appearing at 800–1200 cm–1, following the introduction of either pentagons or heptagons on
armchair edges. This precise spectroscopic identification of pentagons
and heptagons in GNFs provides the groundwork for the analysis of
graphene-related materials.

在原子尺度下识别石墨烯纳米片（graphene nanoflake, GNF）结构中的五边形与七边形，对于全面理解这类材料的化学与物理性质具有重要意义。本研究采用X射线光电子能谱（X-ray photoelectron spectroscopy, XPS）与拉曼光谱，根据引入至石墨烯纳米片锯齿边与扶手椅边的五边形、七边形的位置，分析其光谱特征。当在扶手椅边而非锯齿边引入五边形或七边形时，XPS峰的最大值会向更高结合能方向偏移，且可通过引入的五边形、七边形的位置区分不同结构。拉曼光谱分析结果同样表明，通过拉曼光谱可识别带有引入的五边形或七边形的边的位置：当在扶手椅边引入五边形或七边形后，会在800~1200 cm⁻¹处出现特征谱带。本研究实现了石墨烯纳米片中五边形与七边形的精准光谱识别，为石墨烯相关材料的分析奠定了基础。