Selenium incorporation tuning toward hierarchical flower-like NiSe2@C/MoS2 for high-performance supercapacitor electrodes

NiSe₂ is considered a promising electrode material due to its high theoretical specific capacity and favorable redox activity; however, its practical application is limited by poor electrical conductivity and structural instability during cycling. To overcome these limitations, a sacrificial template method was employed using Ni@C/MoS₂ as the precursor to successfully construct a series of NiSe₂@C/MoS₂ composites with varying selenization degrees. The resulting hierarchical structure exhibits excellent stability and efficiency: the carbon framework significantly enhances electron transport, while MoS₂ not only contributes additional pseudocapacitance but also synergistically improves ion diffusion efficiency. Furthermore, selenium doping effectively modulates the electronic structure and active sites, leading to optimized electrochemical performance. Systematic investigations reveal that when 2 mmol of selenium source is added, the obtained NiSe 2 @C/MoS₂-2 (denoted as NSC/MoS₂-2) electrode achieves an exceptional specific capacitance of 562.3C g −1 (1405.8 F g −1 ) at 1 A g −1 and maintains 82.7 % capacitance retention at 10 A g −1 . An asymmetric supercapacitor assembled with NSC/MoS₂-2 as the positive electrode and activated carbon as the negative electrode delivers a high energy density of 36.37 Wh/kg at a power density of 700 W/kg. This work innovatively demonstrates that precise control of the selenization degree enables the controllable growth of hierarchical NiSe₂ nanoflowers on an MOF-derived carbon framework while establishing strongly coupled heterogeneous interfaces with layered MoS₂. This integrated design markedly improves the structural stability and electrical conductivity of NiSe₂, while fully harnessing the multiple synergistic effects among NiSe₂, MoS₂, and the carbon matrix, thereby delivering comprehensive breakthroughs in specific capacity, superior rate capability, and long-term cycling stability. The strategy offers a new paradigm for the rational construction of high-performance transition metal selenide-based supercapacitor electrodes.