In situ decoration of NiS2 nanoparticles on Ni-BTC nanosheets with enhanced charge storage performance for hybrid supercapacitors

Ni-based metal-organic frameworks (Ni-MOFs) as electrode materials for hybrid supercapacitors face challenges including low actual specific capacity and poor cyclic stability due to their inherent low electrical conductivity and inadequate active site accessibility. Herein, Ni-BTC@NiS 2 heterostructures are designed and synthesized by in situ decoration of NiS 2 nanoparticles onto the surface of Ni-BTC microflowers employing a solvothermal reaction followed by a controlled partial sulfurization treatment. The optimized Ni-BTC@NiS 2 heterostructures as electrode materials demonstrate a maximum capacity value of 604 C g −1 at 1 A g −1 and an initial capacity retention of 91.1 % after 5000 cycles, both of which are significantly higher than those of pure Ni-BTC and NiS 2 electrodes. Furthermore, an assembled two-electrode hybrid supercapacitor device with Ni-BTC@NiS 2 as positive electrode can deliver an maximum energy density of 45.9 Wh kg −1 at 801 W kg −1 . Theoretical and experimental analyses indicate that the integration of Ni-BTC with NiS 2 enhances electronic states near the Fermi level, thereby improving electrical conductivity of Ni-BTC@NiS 2 heterostructures. Meanwhile, a built-in electric field exists at the Ni-BTC/NiS 2 interface, which not only accelerates interfacial charge transport but also enhances surface OH - adsorption, thereby significantly improving charge storage capability. In addition, the surface decoration of NiS 2 nanoparticles on N-BTC microflowers provide additional active sites. Our findings provide a promising strategy for further exploring the application potential of Ni-MOF-based heterostructures in advanced hybrid supercapacitors.