Facile Synthesis of Binary Transition Metal Sulfide Tubes Derived from NiCo‐MOF‐74 for High‐Performance Supercapacitors

Abstract

Recently, binary transition metal oxides, phosphates, and sulfides have attracted wide attention due to their potential applications in supercapacitors. The emergence of metal‐organic frameworks (MOFs) provides new opportunities for the synthesis and investigation of porous binary metal compounds with similar microstructures. Herein, binary metal oxide (NiCo‐O) tubular structures are derived from NiCo‐MOF‐74 via a facile annealing process, and then phosphate (NiCo‐P) and sulfide (NiCo‐S) structures are obtained from NiCo‐O by heat treatment and solvothermal process, respectively. Among the three derivatives, NiCo‐S with nanosheet structures has the highest specific capacitance of 930.4 F g−1 at a current density of 1 A g−1 and an excellent rate capability with a retention of ≈80% at 10 A g−1. The long‐term cycling performance of NiCo‐S is superior with 70.5% retention after 10 000 cycles. The hybrid supercapacitor device with NiCo‐S and activated carbon as positive and negative electrodes delivers a high energy density of 22.6 W h kg−1 at a power density of 800 W kg−1. The excellent performance of NiCo‐S can be attributed to its nanosheet structure, which increases the specific surface area and electroactive sites.