Hierarchical Mo-doped Ni[sbnd]Co hydroxides cauliflower-like microspheres via a rapid microwave hydrothermal synthesis for supercapacitors

Abstract

Transition metal double hydroxide (TMDH) materials have the advantages of low cost, simple preparation, wide variety, and tunable physical and chemical properties, which have broad research prospects in developing and applying high-performance electrode materials. Herein, molybdenum-doped nickel-cobalt double hydroxides (NiCoDH-Mo) were prepared by a rapid one-step microwave hydrothermal method in tens of minutes. Extensive investigations have been conducted on the morphology, crystal structure, and electrochemical properties of nickel‑cobalt double hydroxides with varying concentrations of Mo doping. The incorporation of Mo dopants into NiCoDH-Mo0.50 has yielded the formation of hierarchical cauliflower-like microspheres, which exhibit a significantly enhanced specific surface area of 91.7 m2 g−1 along with an improved electrical conductivity of 0.0233 μS cm−1. Thus, the optimized NiCoDH-Mo0.50 electrode has a high specific capacity of 160.5 mAh g−1 at a current density of 1 A g−1 and can maintain a high specific capacity of 115.3 mAh g−1 when the current density increases by 20 times. Finally, the NiCoDH-Mo cathode and mango seed-derived activated carbon anode were assembled into a hybrid supercapacitor with an energy density of 41.3 Wh kg−1 at a power density of 850 W kg−1, which also exhibits a capacity retention of 84 % after 8000 cycles. Therefore, we provide a facile and efficient strategy to prepare TMDH electrode materials with excellent performance for energy storage systems.