Synthesis of graphene–like phases by laser ablation of micro-crystalline graphite in water suspension

Abstract

The aim of our work was to obtain graphene-like phases (defected graphene, graphene oxide and reduced graphene oxide) as fine suspensions by applying pulsed laser ablation (PLA) to microcrystalline graphite suspension in water medium. The fundamental (λ = 1064 nm), second (λ = 532 nm), third (λ = 355 nm) as well as the fourth harmonic (λ = 266 nm) of a Nd:YAG laser system, 15 ns pulse duration and 10 Hz pulse repetition rate were used in PLA processes. The morphology of the particles was studied by transmission electron microscopy (TEM). Their phase composition and structure were explored by Raman and X-ray Photoelectron spectroscopies, grazing incidence X-ray diffractometry (GIXRD) and high temperature powder X-ray diffraction (HTXRD) and TEM. It can be assumed, in accordance to the XPS, TEM and Raman studies, that the colloids obtained by all experiments contain predominantly rGO and defected graphene, but also some GO, graphite micro-particles, and graphene-like phases. Amorphous carbon is frequently observed in by PLA at λ = 355 nm as well as at λ = 266 nm at high laser beam fluences but it can be found in very small quantities in all specimens. The XPS analysis of the samples revealed a significant increment in the quantity of different oxygen–containing radicals as a function of the fluence, which is a result of the quantity of the sp3–hybridized carbon. Finally, the established PLA procedures have been found to be highly reproducible.