Carbon fiber in situ grown ZIF-67 nanocrystals with excellent electrochemical and interfacial property

Carbon fiber(CF) reinforced flexible composites had a wide range of applications. However, the interfacial adhesion of composites was weak as a result of the smooth and chemically inert CF surface. To settle this issue, this paper described a method to enhance the specific surface area, roughness and wettability of the CF surface by in situ growing Cobalt-based zeolitic imidazolate framework (ZIF-67) nanocrystals and CF reinforced waterborne polyurethane (WPU) composites were prepared by a simple casting method. Scanning electron microscopy clearly revealed uniformly grown ZIF-67 nanoarrays with distinct morphology on the CF surface. As a result, the CF@ZIF-3 electrode exhibited excellent electrochemical property, with specific capacitance reaching 368.2 mF/cm 2 . The reinforcing effect of ZIF-67 with different morphology was further verified through transverse fiber bundle tension test and shear bonding strength measurements, showing improvements of 51.9 and 72.1% respectively, in comparison to the CF/WPU composites due to the unique structure of the ZIF-67 nanocrystals acted as buffer area, effectively relieving stress concentration and altering the direction of crack propagation. As a result, the interfacial properties of the composites were enhanced. Moreover, tensile and tear strengths of CF@ZIF/WPU composites showed remarkable improvement compared to CF/WPU composites. This study presented a potential reinforcement strategy for achieving high-performance CF/WPU composites. Highlights ZIF-67 with different morphologies were grown in situ on the CF surface. CF@ZIF electrode exhibited excellent electrochemical property. ZIF-67 interface layer improved interfacial properties of composites. The tensile strength of the composites improved after ZIF-67 modification. Introduction of ZIF-67 enhanced the tear strength of composites.