Facile synthesis of 2D bimetallic MOF micro/nanostructures for enhanced supercapacitor

Abstract

The two-dimensional (2D) metal-organic framework (MOF) micro/nanostructures have emerged as promising materials for energy storage. Herein, we report a facile synthesis of 2D CoNi(x:y)-MOFs (x:y = 1:0, 1:2, 1:4, 1:6, 1:8, 1:10 and 0:1) via simple stirring reaction of metal salts (CoCl2·6H2O and/or NiCl2·6H2O) and biphenyldicarboxylate (H2BPDC) with the assistance of appropriate content of triethylamine and water. Water not only promotes trimethylamine to deprotonate the carboxylic acid to participate in coordination but also enables trimethylamine to generate hydroxide ions, affecting the composition and microstructure of the products. Compared with Co-MOF, Ni-MOF, and bulk CoNi(1:6)-MOF, the 2D CoNi(1:6)-MOF delivers higher specific capacitance of 455 F g−1/246C g−1 at 0.5 A g−1 owing to its optimal Co/Ni co-doping and unique 2D micro/nanostructure. In addition, the assembled CoNi(1:6)-MOF//AC exhibits high specific capacitance and a maximum energy density of 38.8 Wh kg−1 at a power density of 263.3 W kg−1.