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

Abstract 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 Cu 2+1 O (Cu 2 O 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 Cu 2+1 O and Cu‐MOF, and intimate connection of Cu 2+1 O@Cu‐MOF and CF, the Cu 2+1 O@Cu‐MOF/CF displays enhanced specific capacitance compared to Cu(OH) 2 /CF and Cu 2+1 O/CF (≈2.5 F cm −2 vs ≈0.8 and 0.9 F cm −2 at 2 mA cm −2 ). The quantitative analysis reveals that the capacitance of the Cu 2+1 O@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 Cu 2+1 O@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.