Microwave aided scalable synthesis of sulfur, nitrogen co-doped few-layered graphene material for high-performance supercapacitors

Doping with heteroatoms has become an approach for improving the electrochemical performance of few-layered graphene. In this work, Sulfur-nitrogen co-doped few-layered graphene synthesized from the graphite flakes acid treated with H2SO4 and HNO3 followed by microwave irradiation. Sulfur-nitrogen co-doped few-layered graphene consists of less than 15 graphene layers with a high degree of graphitization. The supercapacitor exhibited a specific energy density of 15 Wh kg−1 at a power density of 300 W kg−1at room temperature in aqueous electrolyte. The S, N-FLG electrodes show the specific capacitance of 298 F g−1 at a current density of 1 A g−1and stable over 10,000 continuous charge-discharge cycles with 95% capacitance retention at 1 A g−1. The obtained capacitance is due to maximum utilization of few-layered graphene sheets, highest intrinsic surface capacitance due to the synergetic effect of the formation of N-S-H hydrogen bonds and S, N co-doping in graphene aromatic rings

Nitrogen phosphorous derived carbons from Peltophorum pterocarpum leaves as anodes for lead–carbon hybrid ultracapacitors

Lead–carbon hybrid ultra-capacitors are emerging as an alternative to a lead-acid battery, owing to the absence of sulfation, thereby enhancing cycle life and C rate performances. In this work, Nitrogen and Phosphorous derived carbons are synthesized from the Peltophorum pterocarpum leaves by treating with phosphoric acid followed by carbonization at 550 °C for 3 hrs. These carbons contain about 3.76% of Nitrogen and 1.26% of Phosphorous and have a BET surface area of 443 m2 g−1. Specific capacitances of 1032 F g−1 and 640 F g−1 at current densities of 1 A g−1 and 10 A g−1, respectively in 4.5 M. sulfuric acid are achieved for these carbon-based electrodes. The hybrid ultra-capacitor fabricated by using PbO2 positive electrode and Nitrogen and Phosphorous derived carbons coated on to graphite sheet as a negative electrode shows cycling stability with capacitance retention of >95% for about 15,000 cycles at an applied current density of 5 A g−1. The pseudocapacitive nature of as-synthesized carbon exhibits significant improvement in electrochemical performance in lead–carbon ultra-capacitors

MgO-decorated few-layered graphene as an anode for Li-ion batteries

10.1021/am5064712ACS Applied Materials and Interfaces742301-230