V-doped NiS@CoMoO4 core–shell heterostructures and their super capacitor properties

Abstract

In this study, V-doped NiS@CoMoO₄ core–shell arrays were fabricated on nickel foam via a two-step hydrothermal method. The results show that vanadium doping effectively modulates the electronic structure of the NiS core, improving its intrinsic conductivity and promoting electron transfer across the NiS–CoMoO₄ interface. The NiS core serves as an efficient electron transport pathway, while the CoMoO₄ shell, with its high specific surface area and porous nature, offers abundant active sites, leading to enhanced ion diffusion and interfacial reaction kinetics. The core–shell architecture not only improves structural stability but also alleviates volume strain during cycling. Electrochemical tests reveal that the (3.0% V)-NiS@CoMoO₄ electrode delivers a specific capacitance of 2559 F g⁻¹ at 1 A g⁻¹, with 93.9% capacitance retention after 10 000 cycles. An asymmetric supercapacitor assembled with this material as the positive electrode and VN@C as the negative electrode operates within a 1.6 V window, achieving an energy density of 66.4 Wh kg⁻¹ and a power density of 800 W kg⁻¹, while retaining 94.9% capacitance after 10 000 cycles. This work demonstrates that the combined strategy of V doping and core–shell heterostructuring can effectively optimize electron transport and interfacial processes, offering a viable approach for designing high-performance supercapacitor electrodes.