One-step radiolytic synthesis of heteroatom (N and S) co-doped graphene for supercapacitors

Abstract

A novel, rapid, one-step electron-beam (EB) based method for both reduction of graphene oxide (GO) and co-doping of nitrogen and sulfur to prepare N, S-codoped graphene layers (NSG) has been achieved. This synthesis process relies on the interaction of high energy EB rays from an electron accelerator with the water in the aqueous solutions containing l-cysteine as the precursor of nitrogen and sulfur, leading to the generation of highly reducing species that not only reduce the GO to reduced graphene oxide (rGO), but also dope nitrogen and sulfur into graphene. The as-prepared heteroatom doped graphene materials own a better dual-doping and reduction of the GO. The range of nitrogen and sulfur doping content could achieve 4.88–10.88 at% and 2.08–4.59 at%, respectively. The sample prepared under the irradiation dose of 210 kGy (NSG-210) exhibits the highest specific capacitance of 227.94 F g−1 at a scan rate of 10 mV s−1 and stable cycling performance with a capacitance retention of 83% after 25,000 cycles at a current density of 10 A g−1. These results exhibit an eco-friendly and simple design of electrode materials for high performance supercapacitors.