Large level of N-doped graphene prepared by facile route with high supercapacitance.

The effect of zinc utilization and the performance characteristics in a zinc–bromine redox flow cell is reported. Simultaneously changing the quality of the electrolyte and the electrode substrate material resulted in an increase in the surface coverage with randomly oriented crystallographic (101) planes and, as a result, the cell exhibited higher Faradaic efficiency.

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Recently, biomass derived carbons have gained enormous attention mainly due to their abundance, the environmental, and cost factors associated with utility in energy conversion and storage systems. The search for new, robust, and economically viable carbon sources that can produce efficient porous carbons with desirable textural properties remains a current focus of research. The present study demonstrates a facile scalable method to produce hierarchical nitrogen-implanted carbon nanosheets (NCNS) with a large surface area of 1297 m 2 g −1 , a pore volume of 0.68 cm 3 g −1 , and mesopores of diameter 4.2 nm from palm spathe biomass (borassus f labellifer). The 2D carbon nanostructures stem from the implantation of alien nitrogen atoms into the aromatic carbon lattice or grafting of N onto the carbon basal planes or edge sites as evident from X-ray photoelectron spectroscopy. The Xray diffraction, field-emission scanning electron microscopy, and highresolution transmission electron microscopy confirmed the 2D nanosheet morphology. The NCNS layered carbon nanostructures have been scrutinized as potential energy storage materials in Li-ion batteries (LIBs) and supercapacitors (SCs). Investigation of NCNS as anode materials in LIBs delivers a high reversible capacity of 477 and 414 mAh•g −1 at 0.1 and 0.2 C rate, respectively, with ∼100% Coulombic efficiency after 100 (dis)charge cycles. Tested as supercapacitors, the NCNS constructed electrode delivers an impressive specific capacitance of 268 and 218 F•g −1 at a applied current of 1 and 5 A•g −1 , respectively. The electrode maintains a remarkable capacity retention of ∼99% Coulombic efficiency after 15 000 (dis)charges using 1 M H 2 SO 4 as an aqueous electrolyte. The NCNS constructed electrode achieved a high energy density of 20.83 Wh•kg −1 with the power density of 37 494 W•kg −1 . Such exquisite properties of biomass derived NCNS are mainly ascribed to a combined effect of 2D sheet morphology, large specific surface area, hierarchical bimodal pore architecture, and implanted nitrogen atoms.

Herein, we demonstrate a simple and unique strategy for the preparation of P-doped into the substructure of mesoporous carbon nitride materials (P-MCN-1) with ordered porous structures as a high-energy and high-power Li-ion battery (LIB) anode. The P-MCN-1 as an anode in LIB delivers a high reversible discharge capacity of 963 mAh g–1 even after 1000 cycles at a current density of 1 A g–1, which is much higher than that of other counterparts comprising s-triazine (C3H3N3, g-C3N4), pristine MCN-1, and B-containing MCN-1 (B-MCN-1) subunits or carbon allotropes like CNT and graphene (rGO) materials. The P-MCN-1 electrode also exhibits exceptional rate capability even at high current densities of 5, 10, and 20 A g–1 delivering 685, 539, and 274 mAh g–1, respectively, after 2500 cycles. The high electrical conductivity and Li-ion diffusivity (D), estimated from electrochemical impedance spectra (EIS), very well support the extraordinary electrochemical performance of the P-MCN-1. Higher formation energy, lower bandgap value, and high Li-ion adsorption ability predicted by first principle calculations of P-MCN-1 are in good agreement with experimentally observed high lithium storage, stable cycle life, high power capability, and minimal irreversible capacity (IRC) loss. To the best of our knowledge, it is an entirely new material with the combination of ordered mesostructures with P codoping in carbon nitride substructure which offers superior performance for LIB, and hence we believe that this work will create new momentum for the design and development of clean energy storage devices.