Temperature dependent Raman modes of reduced graphene oxide: Effect of anharmonicity, crystallite size and defects

A consolidated effect of anharmonicity, crystallite size and defects has been studied using temperature dependent Raman spectroscopy of reduced graphene oxide (rGO). The micro-Raman spectra obtained over a wide temperature range of 173-723 K (below and above room temperature) indicate linear shifts in the peak position of G- and D- modes, with negative temperature coefficients of -0.009 and -0.010 cm(-1) K-1, respectively. The average crystallite size and defect density were calculated and their correlation with the temperature coefficient of G-peak position and line width were discussed. Further, contributions from true-anharmonic and quasi-harmonic parts in shifting the G- and D- peak positions were estimated using theoretical models, which indicate the dominance of true-anharmonic part. Role of electron-phonon, anharmonicity and defect contributions to the temperature dependent variation of line width of G-peak have been discussed. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The temperature dependent Raman spectroscopy of reduced graphene oxide (rGO) reveals the combined effect of anharmonicity, crystallite size, and defects on the peak positions and line widths of G- and D- modes. The dominance of true-anharmonic part in shifting the peak positions is indicated by theoretical models. The contributions of electron-phonon coupling, anharmonicity, and defects to the temperature dependent variation of line width are discussed.