Mo-Doped Ni-Co Selenide Nanosheets as High-Performance Electrodes for Aqueous Ni-Zn Batteries and Supercapacitors

Metal selenides have become prominent electrode materials in aqueous energy storage systems. Nonetheless, improving their electrochemical performance through a simple doping approach and a reasonable structural design remains a significant challenge. In this study, a nickel-cobalt bimetallic selenide with triangular-leaf nanosheet morphology derived from ZIF was synthesized via a two-step process, encompassing ion etching and one-pot doping with selenizing. Due to the rich redox activity and the effective modulation of electronic structure induced by Mo doping, the Mo-(Ni,Co)Se/NF electrode provides a high specific capacity of 1.687 mAh cm-2 at 2 mA cm-2. When paired with commercial zinc foil to form an aqueous nickel-zinc battery, the Mo-(Ni,Co)Se//Zn cell exhibits a high specific capacity of 1.515 mAh cm-2 at 2 mA cm-2 and satisfactory cycling stability (mains at 75.53% after 1000 cycles). Furthermore, upon assembling the Mo-(Ni,Co)Se/NF electrode with activated carbon to construct an asymmetric supercapacitor, the device achieves an energy density of 0.770 mWh cm-2 and retains 99.6% capacity after 10,000 cycles. This study presents an effective and straightforward approach for synthesizing Mo-doped metal selenide nanomaterials for aqueous energy storage devices.