Tuning Zn-ZIF Derivatives via Dual-Anion Hybridization for High-Performance Supercapacitors

Due to their unique electronic structures and polymorphic characteristics, transition metal sulfur compounds and their composite materials have a variety of functions and excellent prospects, which have attracted widespread attention this year, especially in research and application fields such as energy conversion and storage. Among them, the composition and structure of monovalent and binary transition metal sulfur/selenium compounds are relatively less complex. Their electrochemical and other related properties can easily be effectively regulated and optimized due to changes in parameters such as material composition, microstructure, and electronic structure. In the present work, a two-step hydrothermal route was used to construct a multiphase ZnS/ZnSe-MXene heterogeneous composite hybrid material via two-step hydrothermal treatment using ZIF-7 as the precursor. The obtained multidimensional hybrid architecture featuring a unique mesoporous network provides a specific surface area of 10.54 m2 g-1, with an average pore size of 3.68 nm. This optimized porous structure effectively facilitates electrolyte penetration and exposes a considerable number of redox-active sites, enabling the ZnS/ZnSe@MXene electrode to exhibit a gravimetric specific capacitance of 1047.2 F g-1 at a current density of 1 A g-1 with a three-electrode set up, and after experiencing up to 10,000 cycles at a high current density of 10 A g-1, its capacitance retention rate can still reach 88.78% of the initial capacitance. In addition, an asymmetric supercapacitor assembled by using ZnS/ZnSe@MXene serving as the positive electrode and straw-derived homemade activated carbon (AC) acting as the negative electrode can achieve an energy density of 15.5 Wh kg-1 (power density: 750 W kg-1), where energy and power densities are normalized to the total mass of active materials in the positive and negative electrodes. This work confirms that ZnS/ZnSe@MXene hybrid materials have broad prospects as electrode materials for advanced energy storage systems.