Ethanol‐Induced Ni2+‐Intercalated Cobalt Organic Frameworks on Vanadium Pentoxide for Synergistically Enhancing the Performance of 3D‐Printed Micro‐Supercapacitors

The synthesis of metal‐organic framework (MOF) nanocomposites with high energy density and excellent mechanical strength is limited by the degree of lattice matching and crystal surface structure. In this study, dodecahedral ZIF‐67 is synthesized uniformly on vanadium pentoxide nanowires. The influence of the coordination mode on the surface of ZIF‐67 in ethanol is also investigated. Benefitting from the different coordination abilities of Ni2+, Co2+, and N atoms, spatially separated surface‐active sites are created through metal‐ion exchange. Furthermore, the incompatibility between the d8 electronic configuration of Ni2+ and the three‐dimensional (3D) structure of ZIF‐67 afforded the synthesis of hollow structures by controlling the amount of Ni doping. The formation of NiCo‐MOF@CoOOH@V2O5 nanocomposites is confirmed using X‐ray absorption fine structure analysis. The high performance of the obtained composite is illustrated by fabricating a 3D‐printed micro‐supercapacitor, exhibiting a high area specific capacitance of 585 mF cm−2 and energy density of 159.23 µWh cm−2 (at power density = 0.34 mW cm−2). The solvent/coordination tuning strategy demonstrated in this study provides a new direction for the synthesis of high‐performance nanomaterials for electrochemical energy storage applications. The hollow structure is synthesized by controlling the amount of Ni doping by using the different coordination abilities of Ni2+ and Co2+ with N and O atoms and the incompatibility between the d8 electronic configuration of Ni2+ and the 3D structure of ZIF‐67. The composite material applied to 3D printing micro supercapacitor has excellent specific capacitance and energy density.