Facile synthesis of hexagonal single-crystalline ZnCo2O4 nanosheet arrays assembled by mesoporous nanosheets as electrodes for high-performance electrochemical capacitors and gas sensors

Abstract A facile strategy has been developed to realize the controllable synthesis of two dimensional (2D) single crystalline ZnCo 2 O 4 nanosheet arrays (h-ZCO NSs) on the Ni foam surface. According to the SEM, TEM and BET analysis, it was found that the h-ZCO NSs have a hexagonal structure with a thickness of ca. 84 nm, and display a high specific surface area of 94.1 m 2  g –1 with the pore size distribution of ca. 8 nm. As electrochemical capacitor electrode, h-ZCO NSs show large specific capacitance (1004.9 F g −1 at 3.3 A g –1 ), good rate capability and excellent cycling stability (93.5% capacitance retention after 2000 cycles at 10.0 A g –1 ), indicating better electrochemical performance. Additionally, serving as a gas sensor, h-ZCO NSs also exhibit remarkable sensitivity and selectivity towards methanol gas. All these impressive performances suggest that the h-ZCO NSs are a promising electrode material for electrochemical capacitors and gas sensors.