Abstract
Nitrogen doped reduced graphene oxide (N-rGO) metal free catalyst was synthesized by simple sonochemical assisted hydrothermal method with ethylenediamine (EDA). The prepared N-rGO catalyst was characterized using X-ray diffractometer (XRD), UV-visible absorbance spectroscopy (UV-vis), Field emission-scanning electron microscopy (FE-SEM-EDX), individual elemental mapping, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Nitrogen from EDA was doped into the two dimensional graphene sheets during hydrothermal process at 150 degrees C. The maximum amount of N-doping was similar to 25.44 wt%. It was confirmed from XPS spectrum that the prepared N-rGO contains "Pyrollic-N" configuration as a major component. The graphene oxide was reduced into rGO during the synthesis of N-rGO using high frequency (211 kHz) ultrasound in the presence of EDA. The catalytic activity of the prepared catalyst was evaluated through the conversion of 4-Nitrophenol (4-NP) to 4-Aminophenol (4-AP) and the results were monitored using UV-visible spectrophotometer. The N-rGO with predominant pyrollic-N showed high catalytic activity towards the reduction of 4-NP to 4-AR The total reduction of 4-NP (similar to 96%) was achieved within 15 min. This study suggests that the sonochemical assisted hydrothermal method provides a simple alternate way to synthesis metal free N doped graphene catalysts with high N content.