Vertically Oriented Cu2+1O@Cu-MOFs Hybrid Clusters for High-Performance Electrochemical Capacitors

The study of metal-organic framework (MOF) as supercapacitor materials has attracted much attention. Here, a novel vapor-phase approach is developed to in situ grow arrays of Cu2+1O (Cu2O with metal excess defects) @Cu-MOF clusters on copper foam (CF) from the well-aligned Cu(OH)(2) nanorods in response to the exposure in the ligand gas. Benefiting from highly oriented and hierarchical structure of Cu-MOF clusters arrays, synergistic effect between Cu2+1O and Cu-MOF, and intimate connection of Cu2+1O@Cu-MOF and CF, the Cu2+1O@Cu-MOF/CF displays enhanced specific capacitance compared to Cu(OH)(2)/CF and Cu2+1O/CF (approximate to 2.5 F cm(-2) vs approximate to 0.8 and 0.9 F cm(-2) at 2 mA cm(-2)). The quantitative analysis reveals that the capacitance of the Cu2+1O@Cu-MOF/CF is largely contributed by the surface capacitive processes, consisting of double-layer capacitance coming from porous Cu-MOF and Faradaic capacitance rooting from Cu ion. The asymmetric supercapacitor of Cu2+1O@Cu-MOF/CF//AC achieves high energy density of 38.3 Wh kg(-1) at power density of 824.6 W kg(-1) with capacitance retention of 90% after 5000 cycles. This study provides new avenue for in situ growth of MOF as electrodes for supercapacitors, by directly using high conductive metal as precursor through vapor-phase approach, rather than traditional combination of linkers and metal salts in organic solvent.

Automated summary

A novel vapor-phase approach is developed to grow Cu2+1O@Cu-MOF clusters on copper foam, displaying enhanced specific capacitance compared to Cu(OH)(2) and Cu2+1O. The high capacitance of Cu2+1O@Cu-MOF/CF largely comes from surface capacitive processes, leading to excellent supercapacitor performance.