Enhanced supercapacitance behaviour of low energy ion beam reduced graphene oxide

This work reports the reduction of graphene oxide (GO) by low energy ions viz. 100 keV H⁺ 350 keV N⁺ 200 keV Ar⁺ ions with fluences ranging from 5 × 10¹³ to 1 × 10¹⁵ ions cm^-2. The x-ray diffractogram peak of GO decreased with increase in fluence and a broad peak around 25° appeared corresponding to reduced graphene oxide (rGO). Fourier transform infrared spectroscopic results showed the decrease in intensity of oxygen functional groups of GO confirming the reduction of GO which is further corroborated by x-ray photoelectron spectroscopic results. The ratio of D to G band increased with increase in fluence indicating the increase in disorder and formation of a large number of small sp² domains. The work function was increased for low energy ion beam irradiated GO suggesting the storage of more charges. The irradiated GO showed enhanced supercapacitance behaviour with specific capacitance of rGO of 180, 195 and 202 F g^-1 (scan rate 100 mV s^-1) at a fluence 1 × 10¹⁵ ions cm^-2 for H⁺ N⁺ Ar⁺ ions respectively. During irradiation, the ions might have deposited energy through electronic and nuclear energy loss results in the removal of oxygen functional groups from GO and enhancement in supercapacitance performance of rGO. It is also observed that GO irradiated by Ar ions showed more specific capacitance due to larger electronic energy loss than that of other ions.