Controlled Chemical Vapor Deposition for Synthesis of Nanowire Arrays of Metal–Organic Frameworks and Their Thermal Conversion to Carbon/Metal Oxide Hybrid Materials

Metal–organic frameworks (MOFs) can serve as high-surface-area templates to generate hierarchically ordered nanoporous carbon electrodes for high-performance supercapacitor devices. Here we describe a simple chemical approach to synthesize dense three-dimensional (3D) arrays of core–shell [email protected] and Co(CO 3 ) 0.5 (OH)·0.11H 2 [email protected] nanowires on a conductive carbon cloth. Annealing the core–shell structures at high temperatures converted the MOF shell into a composite of nanoporous carbon (NC) mixed with conductive metal oxides. The conformal nature of the MOF-coating process generates a NC film with continuous conductive paths from the outer surfaces of the nanowires down to the flexible carbon electrode. Carbonization of ZIF-67 transforms the material into conductive sp 2 type carbon mixed with Co 3 O 4 nanostructures. Because Co 3 O 4 is a faradic metal oxide with a high theoretical capacitance, these Co 3 O 4 /NC hybrid heterostructure arrays are a promising candidate material for use in an electrochemical supercapacitor device. The Co 3 O 4 /NC hybrid electrodes had good performance and exhibited a high areal capacitance of 1.22 F·cm –2 at 0.5 mA·cm –2 . Conformal deposition of MOFs via the chemical vapor method offers a promising new platform to design conductive, ultrahigh surface area electrodes that preserve the 3D morphology for applications in supercapacitors and electrocatalysis.