Layered CuI-MOFs containing [Mo8O26]4− clusters as supercapacitor electrode materials

We have successfully synthesized two kinetically stable CuI-MOFs with 2D layered architectures by introduction of β-[Mo8O26]4− clusters, denoted as [CuI2(β-Mo8O26)(bnie)2][Cu2(bnie)2] (NAU-1) and [CuI2(bnie)2]2(β-Mo8O26) (NAU-2) respectively. According to the result of electrochemical analysis, all these framework active materials behave as pseudo-capacitor and exhibit high capacitance and excellent energy delivery efficiency. For instance, the maximum gravimetric capacitance of NAU-1 and NAU-2 electrode is 800 and 828 F g−1 at a current density of 1.0 A g−1 separately. Theory mechanism analyses suggest capacitive (i ∝ v) and diffusion-controlled (i ∝ v1/2) currents contribute equally during redox reaction process. Particularly, after integration of carbon-based conductive matrix with CuI-MOFs, the structural stability and cycling life are both promoted. Whether carbon nanotubes or graphene oxide, they both boost the conductivity of the electrode and the capacitance retentions of these electrodes keep growing trends that all surpass 100% after 5000 continuous cycles. The excellent electrochemical performance may be ascribed to the β-[Mo8O26]4− clusters occupying the void space of 2D layered structures that facilitate electron transport and ions transmission.