Solid–solid interface growth of conductive metal–organic framework nanowire arrays and their supercapacitor application†
The chemical vapour deposition (CVD) method has offered a new possibility of preparing metal–organic frameworks (MOFs). However, the reported MOF-CVD method is limited to the use of gaseous organic precursors, preventing the extension of the CVD method to a broad range of potential organic linkers. This study, for the first time, reports a dual-temperature zone CVD-assisted approach for the in situ growth of conductive Cu3(HHTP)2 (HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene) nanowire arrays (NWAs) on the interface between a solid Cu foil and a solid organic precursor, overcoming the difficulties of high sublimation temperatures of organic ligands and low decomposition temperatures of conductive MOFs. In the process, oxygenated water (O-H2O) is the key to obtain crystalline Cu3(HHTP)2 NWAs, and the growth is described by a base-growth mode. A symmetrical supercapacitor based on Cu3(HHTP)2 NWAs on the Cu foil shows a high specific surface area normalized capacitance of 41.1 μF cm−2 for 0.5 A g−1, which is 2–5 times higher than those of most carbon materials. This study demonstrates the extension of the synthesis method from the previous liquid or gas based reaction to a solid–solid reaction, and this extension is expected to be very useful for the production of a broad range of conductive MOFs and their direct supercapacitor application.