Thermal deoxygenation causes photoluminescence shift from UV to blue region in lyophilized graphene oxide

Lyophilized graphene oxide (GO) was thermally exfoliated in stages at predefined temperatures up to 400 degrees C, and photoluminescence (PL) study of GO and thermally reduced GO (TGO) was carried out at each step. A significant red shift in the PL emission peak (412 nm) was found on annealing GO at 400 degrees C in comparison to as-synthesized GO (365 nm). In addition, the PL emission at 457 nm in case of as synthesized GO, which is related to topological defects was quenched conspicuously. Samples were characterized using X-ray photoelectron spectroscopy (XPS), UV-visible spectroscopy, Fourier-transform infrared (FTIR) spectroscopy and Raman spectroscopy. Morphological characterization was performed using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The detailed analysis presented might help in highlighting and understanding the structural changes related to deoxygenation and the PL emission mechanism of graphene derivatives synthesized at lower temperatures. The study can also be used a tool for comprehending tunable PL emissions for future optoelectronic applications.