Ni-MOF Nanosheet-Decorated MnS Hollow Microspheres as a p-n Heterojunction for High-Performance Supercapacitors

Transition metal sulfides are promising electrode materials for supercapacitors (SCs), but they still suffer from sluggish electrochemical kinetics and volume changes during the electrochemical process. Herein, two-dimensional (2D) nickel metal–organic framework (Ni-MOF) nanosheets coated on MnS hollow microspheres to form a MnS@Ni-MOF p-n heterojunction have been constructed for SCs. The core–shell structure can provide abundant electroactive sites and void space benefits electrolyte ions diffusion. The charge redistribution in the p-n junction can form space-charge regions and a built-in field therein, which facilitates charge transfer, thereby enhancing intrinsic activity. Benefiting from these advantages, the optimal MnS@Ni-MOF-5 (12 h) displays outstanding specific capacity (687.0 C g–1 at1 A g–1), surpassing solitary MnS or Ni-MOF. Besides, the asymmetric SC comprising MnS@Ni-MOF-5 (12 h) demonstrates satisfactory energy density (maximal 28.7 W h kg–1) and stability (86.2%, 10,000 cycles at 5 A g–1).