Metal–Organic Framework-Derived Trimetallic Selenide and Sulfide for Fabrication of High-Performance Asymmetric Supercapacitors

MOF-derived transition metal chalcogenides are used as pseudocapacitive electrodes owing to their ability for reversible faradaic redox processes at the electrode/electrolyte interface. In this work, we report the synthesis of MOF-derived Ni–Zr–Co–X (X = Se, S) using a Zr–Co-based MOF as the precursor on Ni foam via in situ growth, hydrothermal ion exchange, selenidation, and sulfidation. Compared with S, Se shows lower electronegativity due to its distinct electronic state, which facilitates more efficient redox reactions. As a result, selenides show superior electrochemical properties compared to those of sulfides. The MOF-derived Ni–Zr–Co–Se and Ni–Zr–Co–S electrodes in a 3-electrode system exhibited capacities of 388.9 and 151 mA h g–1, respectively, at the current density 2 A g–1, and durability of 92.7 and 89.4% after 4000 cycles, respectively. Furthermore, the assembled Ni–Zr–Co–Se and Ni–Zr–Co–S//activated carbon asymmetric supercapacitors, in which activated carbon and nickel foam acted as the negative electrode and Ni–Zr–Co–Se and Ni–Zr–Co–S positive electrode, demonstrated specific energy densities of 71 and 52 W h kg–1 at the power densities of 944.4 and 935.3 W kg–1, respectively. In addition, the Ni–Zr–Co–Se//activated carbon maintained 90.1% of its initial capacity after 4000 cycles, showing excellent durability.