Protonated Emeraldine Polyaniline Threaded MIL-101 as a Conductive High Surface Area Nanoporous Electrode

Abstract

The low electrical conductivity of metal organic frameworks (MOFs) is currently the major hurdle for their electrochemical applications. Herein, we render an MOF with a 9-order magnitude higher electrical conductivity by threading a conductive polymer in the MOF cavities at molecular scale. Such electrically conductive MOF–protonated emeraldine polyaniline (PANI) threaded in MIL-101(Cr), PANI∼MIL-101, demonstrates superb electrical conductivity of 0.01 S cm–1 with the ultrahigh surface area retained (2065 m2 g–1) because of the full penetration of PANI and its uniform distribution within MIL-101 cavities. Effective electron transport is established in the PANI∼MIL-101 structure via π–π stacking among polyaniline chains and n → π* and π–π interactions between polyaniline and MIL-101. We demonstrate PANI∼MIL-101 is an effective electrode in Fe-ion sensors and all-Fe redox flow batteries. One coating of this conductive MOF can serve as alternate for a microelectrode array. This work now opens up a new class of conductive MOFs with high surface area and nanoporosity, which are promising for electrochemical applications.