Designing of Kirkendall Effect Assisted CoFe : WS 2 Nanoboxes for Dye‐sensitized Solar Cell and Supercapacitor Applications

In this study, CoFe: tungsten disulfide (WS2) hollow nanoboxes were synthesized for dye-sensitized solar cell (DSSC) and supercapacitor (SC) applications. Hollow nanoboxes structured as CoFe: WS2 were synthesized using the facile hydrothermal and co-precipitation methods, combined with the ultrasonication technique as a pioneer. The morphological transformation from nanocubes to hollow nanoboxes (Kirkendall effect) was observed upon the incorporation of WS2 quantum dots in an optimal ratio. The CoFe: WS2-2 hollow nanoboxes were employed as the counter electrode (CE) in DSSCs, which exhibit phenomenal catalytic activity in I-3(-) electrolyte reduction and achieved a maximum power conversion efficiency (PCE) of 5.7%. Increased active sites for red-ox reaction and enhanced surface area due to the Kirkendall effect made the power conversion of the CoFe: WS2-2 DSSC device superior to that of platinum devices (4.0%). Supercapacitor performance of the CoFe: WS2-2 hollow nanoboxes shows a maximum specific capacitance of 551 F/g at a Current density of 1 A/g and the capacitance retention was noticed to be 88.96% in the three-electrode system using 2 M KOH as electrolyte. The asymmetric supercapacitor device exhibits an energy density of 37.18 Wh/kg and a power density of 875 W/kg at a current density of 1 A/g. The constructed CoFe: WS2-2//AC device reveals capacitance retention and coulombic efficiency of 71.99% and 98.18% after 6000 cycles, in the SC, respectively. The result emphasizes that hollow nanoboxes structured CoFe: WS2-2 can be an outstanding electrode in both DSSCs and SCs devices.