Synergistic MOF-on-MOF Integration for Enhanced Energy Storage Performance.

Transition-metal-based metal-organic frameworks (MOFs), especially Ni-MOFs, have emerged as attractive candidates for electrochemical energy storage owing to their considerable theoretical specific capacitance. However, their poor electrical conductivity severely limits the overall electrochemical performance in supercapacitors. By virtue of the excellent conductivity of conductive MOFs (cMOFs), in this work, a series of MOF-on-MOF heterostructures were fabricated by integrating cMOFs M-HHTP (M = Ni, Co; HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene) with Ni-MOFs (Ni-BTC, Ni-BDC; H₃BTC = trimesic acid, H₂BDC = terephthalic acid). Electrochemical tests reveal that all of the composites exhibit enhanced energy storage performance compared to that of the pristine MOFs, with Co-HHTP@Ni-BDC demonstrating the most outstanding performance in the application of aqueous asymmetric supercapacitors.