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

335 This novel 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 graphene oxide to graphene, but also dope nitrogen and sulfur into graphene instead of oxygen. 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 and stable cycling performance with a capacitance retention of 83% after 25,000 cycles at a current density of 10 A g−1.