Cation-coupled electron hopping through metal-organic frameworks – from fundamentals to applications

Metal-organic frameworks (MOFs) are porous, crystalline 3-dimensional materials constructed from defined metal fragments and interconnecting organic linker molecules. If the linkers are redox active, electrons can propagate through the MOF by an electron hopping mechanisms.

This electron hopping needs to be accompanied by the translocation of charge-balancing counter cations, a process that is often more sluggish than the actual electron hopping, thereby limiting overall charge transport.Accelerating cation-coupled electron hopping transport (CCEHT) is not only fundamentally interesting, but essential for applications of MOFs in redox catalysis, photoelectrocatalysis and advanced electronics applications.

We will synthetically engineer proton conductivity into MOFs to substitute traditional cation transport, thereby accelerating overall electron hopping transport.

Facilitated charge transport will be exploited for the construction of highly active electrocatalytic hydrogen evolving MOFs.

The most active MOFs will be grown on semiconductors to driven catalysis photoelectrochemically at an applied potential that is ca. 500 mV more positive than that of a dark electrode.

Finally, MOFs that conduct by CCEHT do not feature electronic bands and cannot be treated with traditional band structure theory. Instead, such MOFs are redox conductors.

We will exploit this entirely unexplored insight by constructing MOFs that can be switched between insulator and semiconductor conductivity.