Enhanced Electrochemical Performance of Binder-Free Fluorine-Vanadium-Doped CoMoO₄ Nanosheets via In Situ MXene...

Designing an affordable device that seamlessly combines efficient electrochemical energy storage with straightforward, robust protocols represents a promising pathway for ushering in the next generation of green power solutions and fostering a sustainable society. In this work, CoMoO₄, vanadium-doped CoMoO₄ (V-CoMoO₄), and fluorine-vanadium-doped CoMoO₄ (F-V-CoMoO₄) were synthesized in situ on nickel foam (NF) using a hydrothermal method, followed by thermal treatment, resulting in a hierarchical structure with interconnected nanosheets and open porous channels. V₂C MXene was used as the vanadium source, which was fully oxidized during the synthesis. This unique architecture is particularly advantageous for supercapacitor applications, as it facilitates efficient electrolyte flow, promotes the formation of oxygen defects that enhance ion transport, and ultimately maximizes electrochemical performances. At a current density of 2.5 mA/cm², the F-V-CoMoO₄ electrode achieves an areal capacitance of approximately 2250 mF/cm² (900 F/g at 1 A/g), outperforming pristine CoMoO₄ (180 mF/cm², 72 F/g) and V-doped CoMoO₄ (810 mF/cm², 324 F/g). An asymmetric supercapacitor is fabricated using an F-V-CoMoO₄@NF//AC@NF device and PVA/KOH gel electrolyte, showing excellent redox behavior and cycling stability, with 100% capacity retention after 2000 cycles at a current density of 1 Ag^-1. Moreover, the developed device exhibits a specific energy density of 11.5 Whkg^-1 and a power density of 225 Wkg^-1 at a current density of 0.3 A/g. These findings highlight the potential of F-V doping in enhancing the electrochemical properties of CoMoO₄-based electrodes.