Enhanced Electrochemical Performance of Binder-Free Fluorine–Vanadium-Doped CoMoO4 Nanosheets via In Situ MXene Integration for Energy Storage Applications

Designing an affordable device that seamlessly combines efficient electrochemical energy storage with straightforward, robust protocols represents a promising pathway for next-generation green power solutions. Here, CoMoO4, V-doped CoMoO4, and fluorine–vanadium-doped CoMoO4 (F-V-CoMoO4) are synthesized in situ on nickel foam by a hydrothermal method followed by thermal treatment, yielding hierarchical nanosheets with open porous channels. V2C MXene is used as the vanadium source and fully oxidized during synthesis. The F-V-CoMoO4 electrode delivers ≈2250 mF cm⁻² at 2.5 mA cm⁻² (≈900 F g⁻¹ at 1 A g⁻¹), surpassing pristine CoMoO4 and V-CoMoO4. An asymmetric supercapacitor (F-V-CoMoO4@NF//AC@NF) with PVA/KOH gel shows excellent redox behavior, 100% capacity retention after 2000 cycles at 1 A g⁻¹, and achieves ~11.5 Wh kg⁻¹ at ~225 W kg⁻¹. DFT indicates V and F doping increases DOS near the Fermi level and reduces the work function (from ~6.3 eV to ~5.6 eV), enhancing charge transfer. These results highlight F–V doping as a route to high-performance CoMoO4-based electrodes for supercapacitors.