Tratamento térmico a baixa temperatura em dispersões de Óxido de Grafeno: uma análise de suas propriedades ópticas e elétricas

Abstract

In this work, the impact of low-temperature thermal treatment on the optical and electrical properties of graphene oxide (GO) dispersions with different structures was studied. Two types of graphene oxide were synthesized and characterized: one rich in carbonyl groups (CGO) and another rich in hydroxyl groups (HGO). After synthesis, the materials were dispersed in deionized water and subjected to thermal treatment at 80°C for seven days. Significant changes in the optoelectronic properties of the materials were observed, associated with the diffusion process of the oxygenated groups through the GO plane. Over time, the thermal treatment promoted the diffusion of these groups, forming clusters of sp3 carbon and consequently larger regions of sp2 carbon This phenomenon is previously reported in the literature, but it is still underexplored. Results from Raman spectroscopy, Fourier transform infrared (FTIR) absorption spectroscopy, and ultraviolet-visible (UV-Vis) absorption spectroscopy confirm that the two types of graphene oxide synthesized in this work have distinct chemical structures. Additionally, the temperature-treated samples were analyzed using UV-Vis, Raman, current-voltage, and impedance techniques, with the optical bandgap determined using the Tauc method. All results indicate that the thermal treatment efficiently promoted the diffusion of oxygenated groups in all analyzed samples and demonstrate that the GO structure directly impacts this phenomenon.