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

Abstract

A diiron [FeFe]-hydrogenase model complex tethered with a maleimide group, FeFe1, 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 FeFe1@PMO. The coordination structure of the FeFe1 complex and the ordered pore structure were almost completely preserved even after immobilization of FeFe1 on SH-PMO. The FeFe1@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 FeFe1 catalyst (TON = 180) and conventional diiron complexes immobilized on solid supports (TON = 6-18). The increased TON for FeFe1@PMO compared to the homogeneous FeFe1 was attributed to the improvement in the stability of the FeFe1 complex by immobilization on the pore surface of SH-PMO. A [Ru(bpy) 3 ] 2 + photosensitizer tethered with a maleimide (Ru1) was prepared and co-immobilized on FeFe1@PMO to form an all-solid-state photocatalyst FeFe1-Ru1@PMO. FeFe1-Ru1@PMO evolved H 2 without the additional [Ru(bpy) 3 ] 2 + photosensitizer, suggesting efficient photoinduced electron transfer from the immobilized Ru1 to the immobilized FeFe1.

Cobaloxime tethered pyridine-functionalized ethylene-bridged periodic mesoporous organosilica as an efficient HER catalyst

“…The material showed a greater TON than the homogenous system due to the improvement of the stability of the [FeFe]-complex on the pore surface of the PMO. 43 Taking this into consideration, PMOs with appropriate functional groups in their framework could act as excellent scaffolds for assembling other HER catalysts. Inmobilizing cobaloxime molecular complexes within PMO-supports with high surface areas and porous structures of a tailored hydrobicity/hydrophility could increase the stability of the cobaloxime catalyst confined into de mesopores and allow the easy catalyst recycling by filtration.…”

Hydrogenase and Nitrogenase: Key Catalysts in Biohydrogen Production

“…Diiron complexes as mimic [FeFe] hydrogenase have been successfully immobilized on a metal–organic framework (MOF) or mesoporous silica (MS). Periodic mesoporous organosilica (PMO) with thiol groups (SH-PMO) was also developed for artificial [FeFe] hydrogenase anchoring for turnover number (TON) improvement [ 149 ].…”

Artificial Photosynthesis: Current Advancements and Future Prospects

“…Biomimetic models anchored onto heterogeneous supports, such as metal–organic frameworks (MOFs) and silica-based materials, have shown significant promise for their potential in artificial photosynthesis applications as well [ 230 , 231 , 232 , 233 , 234 , 235 , 236 , 237 , 238 ]. MOFs, with their flexible structure and high surface area, can provide an ideal environment for biomimetic complexes.…”