Scouting the supercapacitor performance of bimetallic transition metal co-doped carbon quantum dots (CQDs) Polyvinyl alcohol (PVA) composites as green electrode materials.

Abstract

Abstract Carbon quantum dots (CQDs) have emerged as an excellent and fantastic material among nanomaterials especially in the fabrication of green electrode materials in supercapacitors. The energy storage performance and cyclic stability together with the integration of transition metals enhances its applications in the arena of energy conversion and storage. The present work highlights the fabrication of bimetallic transition metal co-doped CQDs and its composites with Polyvinyl alcohol (PVA), its analytical characterization and the investigation on the electrochemical performances of these composites by Cyclic Voltametric (CV) studies. Co doping of first row transition elements with CQDs were found to enhance the supercapacitor performance by several folds and among the first row transition metals, Mn2+ was found to be superior over others and in the present work, we have synthesized a series of bimetallic transition metal co-doped CQDS by fixing Mn2+ as one of the transition metal ion and the combinations of Mn2+ - Fe2+, Mn2+-Co2+,Mn2+- Ni2+,Mn2+-Cu2+ and Mn2+Zn2+ ions. The formation of bimetallic CQDs were confirmed from the UV- Visible spectral analysis, EDS analysis, fluorescence measurements and the SEM analysis. The high-resolution TEM images reveal that the bimetallic co-doped CQDs were homogeneously distributed and are almost found to be hexagonal in shape possessing a size range of less than 20 nm. The surface area, pore volume and the pore diameter of the composite materials were found to be in the range of (81x10− 2-92 x10− 2) m2/g to (198x10− 3 -202x10− 3) cm3/g and (7.83–8.89) nm respectively. The capacitance value of the bimetallic transition metal co-doped CQDs were found to be in the range of (171–480) µF/cm2, which is found to be enhanced by 200-fold in comparison to single transition metal CQDs and these materials will find wide application towards the fabrication of green electrode materials in near future.