Enhancing supercapacitor performance with biomass-derived activated carbon interlinked CoS2 embedded graphitic carbon nitride

Abstract

This work investigates the improved electrochemical performance of CoS2 on composites CoS2/AC and CoS2/AC/g-C3N4 that are prepared via hydrothermal method and the production of activated carbon is of bio-derived configuration. The structural, vibrational modes, and functional groups of the as synthesized nanostructures are confirmed through X-ray Diffraction (XRD), Raman, and FTIR analyses. The specific surface area of CoS2/AC and CoS2/AC/g-C3N4 is 54.3 m2g−1, and 41.3 m2g−1, respectively. X-ray Photoelectron Spectroscopy (XPS) reveals the charge state of Co2+ and high charge transfer between Co and C in CoS2/AC/g-C3N4 compared to CoS2/AC. Nanoprobe Projection X-ray microscopy (PXM) discloses distorted octahedral coordination of Co2+ and site-dependent charge transfer by Co in CoS2/AC in comparison with CoS2/AC/g-C3N4. Further, the CoS2/AC electrode demonstrates a high specific capacity of 984 Fg−1 in the three-electrode system. The high-performance CoS2/AC electrode produced a high-power density of 2042.21 W Kg−1 and an energy density of 28.36 Whkg−1 in an aqueous electrolyte. The integration of CoS2 nanoparticles into the CoS2/AC and CoS2/AC/g-C3N4 composite framework significantly contributes to the improvement of specific capacity and excellent cycle stability up to 5000 cycles. This improvement could be influenced by several factors, such as reduced ion transport distances, strengthened interfacial interactions, high surface area, distortion of octahedral coordination of Co2+, and spatial-dependent charge transfer by Co in CoS2/AC. The distinct characteristics in specific capacity and cycling stability is attributed to the incorporation of CoS2 nanoparticles within the CoS2/AC and CoS2/AC/g-C3N4 composites that cause the short transport distance of the ions, enhanced interfacial interaction, and further provide better structural stability of the CoS2/AC and CoS2/AC/g-C3N4 composite network.