Graphene Quantum Dots Embedded in NiCo₂S₄/MWCNT Nanocomposite as a Promising Candidate for Supercapacitors and i ₃-Reduction in Dye-Sensitized Solar Cells

Nickel Cobalt Sulfide (NCS) along with Graphene Quantum Dots (GQDs) and Multiwalled Carbon Nanotubes (MWCNTs) are used here for the Counter Electrode (CE) to replace the conventional Pt in a Dye- Sensitized Solar Cell (DSSC). The usefulness of this system in the design of supercapacitors is also investigated. Various analytical tools are used to explore the crystallinity, morphology, and valence states of the synthesized nanocomposites. A short circuit current (JSC) of 11.57 mA/cm2, an open-circuit voltage (VOC) of 0.74 V, and a power conversion efficiency (PCE) of 5.84% are achieved for GQDs embedded NCS/MWCNT nanocomposite which is 39% higher compared to the pristine NCS (3.52%). The obtained PCE is compared with the standard Pt CE (μ6.88%) based DSSCs. Besides, cyclic voltammetry and galvanostatic charge-discharge characteristics are also done to study the supercapacitor performance. The specific capacitance of 448 F/g and 361 F/g at 2 A/g have been achieved with and without a GQDs implanted NCS/MWCNT nanostructure. This research suggests that GQDs implanted NCS/MWCNT is not only a Pt-free DSSC replacement but also has storage capability.