Microwave assisted hydrothermal synthesis of N doped graphene for supercapacitor applications

Nitrogen doped graphene (N-G) has emerged as an important candidate for a plethora of sustainable future applications in recent years. Adatom doping of graphene results in significantly improved physical and chemical properties there by increasing its efficiency for multiple applications. In this work N-G has been synthesized in <6 min using 6-layered Graphene oxide (GO) and urea in a microwave digestion tank (DC). Under microwave irradiations, hydrothermal environment was created in DC while covered vessel (OP) sample was synthesized at atmospheric pressure. This leads to incorporation of significant amount of nitrogen (1.90 %) within graphene in DC sample as compared to the OP sample. The morphological, chemical and structural analysis of synthesized samples was done using Scanning Electron Microscopy, X-ray Diffraction, Fourier Transform Infrared spectroscopy and X-ray Photoelectron spectroscopy analysis. The (ID/IG) ratio obtained from Raman analysis reveals the presence of defect structures in the synthesized samples. Further, the electrochemical supercapacitance performance was checked for the synthesized samples in 1 M H2SO4 acidic electrolyte. Amongst all the samples prepared, DC400 showed good specific capacitance of 97.05 Fg−1 at scan rate of 2 mV/s. Detailed analysis shows that the samples have pseudocapacitive behavior and enhanced charge storage capacity indicating effective nitrogen infusion in GO. The bonding configuration of doped N atoms plays a key role in enhancing electrochemical properties of N-G. Hence, DC400 sample can be utilized efficiently as an electrode material for supercapacitor applications.