Anisotropic Redox Conductivity within a Metal–Organic Framework Material

2019 
Engendering electrical conductivity in otherwise insulating metal-organic framework (MOF) materials is key to render-ing these materials fully functional for a range of potential applications, including electrochemical and photo-electrochemical catalysis. Here we report that the platform MOF, NU-1000, can be made electrically conductive via re-versible electrochemical oxidation of a fraction of the framework’s tetra-phenylpyrene linkers, where the basis for con-duction is redox hopping. At a microscopic level, redox hopping is akin to electron self-exchange and is describable by Marcus’ well-known theory of electron transfer. At a macroscopic level, the hopping behavior leads to diffusive charge transport and is quantifiable as an apparent diffusion coefficient, Dhopping. Theory suggests that the csq topology of NU-1000, together with its characteristic 1D mesopores, will result in direction-dependent, i.e. anisotropic, electrical conduc-tivity. Detailed computations suggest that the governing factor is t...
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