New functionalizaed graphene oxide based on a cobalt complex for black electrophoretic ink applications

Abstract

Graphene functionalized with a cobalt complex containing 2-methyl-imidazole (GO-2-me-imi-Co) was synthesized for the first time. The morphology and structure of the synthesized pigment for application as a black electronic ink were investigated using Fourier-transform infrared spectroscopy, thermo-gravimetric analysis, high resolution transmission electron microscopy, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and electron paramagnetic resonance. In this study, the presence of Co³⁺ and Co¹⁺, especially Co³⁺, along with the positive charge of imidazole groups in the structure, resulted in a positive surface charge and led to a 3D structure. The results obtained from the ζ-potential test revealed a 67% improvement for GO-2-me-imi-Co pigments in comparison with graphene oxide. In addition, the increase in mobility for GO-2-me-imi-Co pigments in tetrachloroethylene as a solvent was reported to be 0.1 μm cm V⁻¹ s⁻¹.