A Heterogeneous Hydrogen‐Evolution Catalyst Based on a Mesoporous Organosilica with a Diiron Catalytic Center Modelling [FeFe]‐Hydrogenase

A diiron [FeFe]‐hydrogenase model complex tethered with a maleimide group, FeFe 1 , was covalently grafted on the pore surface of a periodic mesoporous organosilica with thiol groups (SH‐PMO) to form an efficient heterogeneous hydrogen (H 2 )‐evolution catalyst FeFe 1 @PMO. The coordination structure of the FeFe 1 complex and the ordered pore structure were almost completely preserved even after immobilization of FeFe 1 on SH‐PMO. The FeFe 1 @PMO promoted photocatalysis for H 2 evolution in water containing a photosensitizer [Ru(bpy) 3 ] 2+ , with a turnover number (TON) of 310 over 120 min. The TON was greater than those of an analogous homogeneous FeFe 1 catalyst (TON=180) and conventional diiron complexes immobilized on solid supports (TON=6–18). The increased TON for FeFe 1 @PMO compared to the homogeneous FeFe 1 was attributed to the improvement in the stability of the FeFe 1 complex by immobilization on the pore surface of SH‐PMO. A [Ru(bpy) 3 ] 2+ photosensitizer tethered with a maleimide (Ru 1 ) was prepared and co‐immobilized on FeFe 1 @PMO to form an all‐solid‐state photocatalyst FeFe 1 ‐Ru 1 @PMO. FeFe 1 ‐Ru 1 @PMO evolved H 2 without the additional [Ru(bpy) 3 ] 2+ photosensitizer, suggesting efficient photoinduced electron transfer from the immobilized Ru 1 to the immobilized FeFe 1 .