Detailed in situ TEM/EELS analysis of laser-induced reduction of graphene oxide

Laser-induced reduction of graphene oxide (GO) represents a highly promising approach to graphene synthesis due to local control of the treated area, avoidance of hazardous chemical reagents, and environmentally benign ambient conditions. In this study, we present a comprehensive investigation of the reduction of GO induced by multiple laser pulses at a wavelength of 532 nm by in situ transmission electron microscopy. By systematically varying the laser fluence from 6.36 mJ/cm 2 to 15.88 mJ/cm 2 and employing electron energy loss spectroscopy (EELS), we achieved precise quantification and identification of the removal of distinct oxygen functional groups. The kinetics of the process are modelled using a double-exponential function to determine photoreduction rates as a function of laser fluence. We estimate laser fluences in this range raise the film temperature from 342 °C to 823 °C, and correlate this with observed functional group removal and established thermal decomposition thresholds. Our work offers a detailed understanding of the laser-induced reduction process and highlights the potential for tailoring the chemical composition of graphitic oxides through controlled laser processing.