Improving water dispersibility of non-covalent functionalized reduced graphene oxide with l-tryptophan via cleaning oxidative debris

Abstract

Non-covalent functionalized reduced graphene oxide (rGO) with l-tryptophan was rapidly fabricated by reducing graphene oxide (GO), using l-ascorbic acid as reducer under microwave heating. Atomic force microscope, scanning electron microscope, ultraviolet–visible spectroscopy, X-ray diffraction, Raman spectroscopy and Fourier transform infrared spectroscopy were employed to investigate the morphologies and structures of the samples. The average particle sizes and zeta potentials of rGO were measured by means of dynamic light scattering spectroscopy. Furthermore, the maximum dispersibility of rGO dispersion was calculated from Lambert–Beer law. It was shown that oxidative debris of GO were cleaned after ammonia wash process, and ultimately improving the water dispersibility through enhancing the π–π interaction between l-tryptophan molecules and rGO sheets. The maximum dispersibility of the functionalized rGO dispersion with cleaning oxidative debris was increased by 95 % (from 0.44 to 0.86 mg mL−1) compared to that without cleaning oxidative debris. This investigation proposed an effective method to fabricate the non-covalent functionalized rGO, as well as the method to improve its water dispersibility.