Enhanced photocatalytic hydrogen evolution with a Mixed-Valence iron Metal-Organic framework

Fe-oxo cluster-based metal–organic frameworks (MOFs) offer a tunable platform for visible-light-driven catalysis, yet the unmatched energy level and the ease of charge recombination strongly hinder their application in photocatalytic H2 generation. In this work, we report an Fe(II/III) mixed-valence catalyst derived from the transition of an Fe(II)2N2O10 cluster-based MOF in water through a solvent displacement pathway. Both electronic band structure and charge transfer dynamics are effectively optimized via heteroatom coordination and valence mixing in the iron clusters. 25 times the visible-light-induced H2 yield of pristine FeMOF was obtained by Fe(II/III) MOF with platinum as cocatalyst. The Fe MOF catalyst also shows significantly superior performance in comparison with the well-known oxide catalyst α-Fe2O3 and the commonly investigated MOF catalyst NH2-UiO-66. This work provides a direction for the structural engineering of Fe-MOFs for photocatalysts.