Ultra-fast Proton Conduction and Photocatalytic Water Splitting in a Pillared Metal–Organic Framework

Proton-exchange membrane fuel cells enable the portable utilization of hydrogen (H₂) as an energy resource. Current electrolytic materials have limitation, and there is an urgent need to develop new materials showing especially high proton conductivity. Here, we report the ultra-fast proton conduction in a novel metal-organic framework, MFM-808, which adopts an unprecedented topology and a unique structure consisting of two-dimensional layers of {Zr₆}-clusters. By replacing the bridging formate with sulfate ligands within {Zr₆}-layers, the modified MFM-808-SO₄ exhibits an exceptional proton conductivity of 0.21 S·cm^-1 at 85 °C and 99% relative humidity. Modeling by molecular dynamics confirms that proton transfer is promoted by an efficient two-dimensional conducting network assembled by sulfate-{Zr₆}-layers. MFM-808-SO₄ also possesses excellent photocatalytic activity for water splitting to produce H₂, paving a new pathway to achieve a renewable hydrogen-energy cycle.