Reverse synthesis of star anise-like cobalt doped Cu-MOF/Cu2+1O hybrid materials based on a Cu(OH)2 precursor for high performance supercapacitors

Metal-organic frameworks (MOFs) have attracted increasing attention due to their high specific area and abundant redox sites for application in energy storage devices. However, the non-ideal capacity, poor mechanical/chemical stability, random arrangement and low conductivity of most MOFs largely thwart their extensive applications. Hence, designing an easily operated and highly efficient strategy to address these issues has realistic meanings. Herein, a vertically oriented Cu(OH) 2 nanorod array was selected as both the template and precursor to synthesize highly oriented star anise-like Co-doped Cu-MOF/Cu 2+1 O (Cu 2+1 O refers to the Cu 2 O with metal excess defects) nanohybrid materials, where the MOF structure is formed through an in situ reverse transformation process. Due to the high conductivity resulting from the presence of "excess copper" and doped cobalt ions, as well as the intimate connection between the Cu-MOF and Cu 2+1 O, the optimized (0.1Co/Cu-MOF/Cu 2+1 O) electrode delivers a high areal capacity of 1.548 F cm -2 (518.58 F g -1 ) and remarkable cycling stability (97.26% after 5000 cycles). Meanwhile, the assembled 0.1Co/Cu-MOF/Cu 2+1 O//activated carbon hybrid supercapacitor shows an outstanding energy density up to 25.67 W h kg -1 at a power density of 740.44 W kg -1 . Therefore, the proposed strategy may open a new avenue to unlock the inherent advantages of MOFs for application in the electrochemical energy storage field.