Physico-Chemical Nanomaterials Science

Principal Component Analysis Reveals New Band of Raman Spectra of Reduced Graphene Oxide 
Abakumov A.A., Bychko I.B., P.E. Strizhak
1Department of catalytic synthesis based on single-carbon molecules, L.V. Pisarzhevskii Institute of Physical Сhemistry of the NAS of Ukraine.
Prospect Nauki, 31, Kyiv-03028, Ukraine. 
E-mail: abakumov0aa@gmail.com
Raman spectroscopy is one of the most informative techniques that is applied in the structural analysis of reduced graphene oxide (RGO). Major bands in Raman spectra of RGO are located in 1000–1700 cm-1 interval and presented by high-intensity peaks D (at ~1350 cm-1) and G (at ~1600 cm-1). Minor bands of D* and D” were obtained as a result of curve fitting [1]. However, detection of minor-intensity bands may be performed using principal component analysis (PCA). Applying PCA allows increasing the signal-to-noise ratio significantly so that one may clearly indicate the signal. A set of 7 samples of hydrazine-reduced and thermally treated GO was synthesized for the revision of the Raman spectra of RGO. Obtained Raman spectra was processed by PCA algorithm. The analysis of the dependence of Loadings of the 1st component that contains 93.7% of total variance on Raman Shift given on Figure 1 clearly shows the presence of D* and D” bands as well as new broad band in the range of 1200–1300 cm-1 denoted as DAr. New band may be attributed to aromaticity disruption and formation of small aromatic domains.
	
Figure 1. Dependence of Loadings of 1st Principal Component (PC1) on Raman Shift.	
Literature:
1.	S. Claramunt et al. The Importance of Interbands on the Interpretation of the Raman Spectrum of Graphene Oxide. J. Phys. Chem. C. 2015, 119(18), 10123–10129.