2D MOF Nanoflake-Assembled Spherical Microstructures for Enhanced Supercapacitor and Electrocatalysis Performances

摘要

Metal–organic frameworks (MOFs) are of great interest as potential electrochemically active materials. However, few studies have been conducted into understand-ing whether control of the shape and components of MOFs can optimize their electrochemical performances due to the rational realization of their shapes. Component control of MOFs remains a significant challenge. Herein, we demon-strate a solvothermal method to realize nanostructure engi-neering of 2D nanoflake MOFs. The hollow structures with Ni/Co-and Ni-MOF (denoted as Ni/Co-MOF nanoflakes and Ni-MOF nanoflakes) were assembled for their electrochemi-cal performance optimizations in supercapacitors and in the oxygen reduction reaction (ORR). As a result, the Ni/Co-MOF nanoflakes exhibited remarkably enhanced performance with a specific capacitance of 530.4 F g-1 at 0.5 A g-1 in 1 M LiOH aqueous solution, much higher than that of Ni-MOF (306.8 F g-1) and ZIF-67 (168.3 F g-1), a good rate capability, and a robust cycling performance with no capacity fading after 2000 cycles. Ni/Co-MOF nanoflakes also showed improved electrocatalytic performance for the ORR compared to Ni-MOF and ZIF-67. The present work highlights the sig-nificant role of tuning 2D nanoflake ensembles of Ni/Co-MOF in accelerating electron and charge transportation for opti-mizing energy storage and conversion devices.