Photocatalytic Hydrogen Evolution from Rhenium(I) Complexes to [FeFe] Hydrogenase Mimics in Aqueous SDS Micellar Systems: A Biomimetic Pathway

Abstract

To offer an intriguing access to photocatalytic H2 generation in an aqueous solution, the hydrophobic photosensitizer, Re(I)(4,4′-dimethylbpy)(CO)3Br (1) or Re(I)(1,10-phenanthroline)(CO)3Br (2), and [FeFe] H2ases mimics, [Fe2(CO)6(μ-adt)CH2C6H5] (3) or [Fe2(CO)6(μ-adt)C6H5] (4) [μ-adt = N(CH2S)2], have been successfully incorporated into an aqueous sodium dodecyl sulfate (SDS) micelle solution, in which ascorbic acid (H2A) was used as a sacrificial electron donor and proton source. Studies on the reaction efficiency for H2 generation reveal that both the close contact and the driving force for electron transfer from the excited Re(I) complexes and [FeFe] H2ases mimics are crucial for efficient H2 generation with visible light irradiation. Steady-state and time-resolved investigations demonstrate that the electron transfer takes place from the excited Re(I) complex 1 or 2 to [FeFe] H2ases mimic catalyst 3, leading to the formation of the long-lived Fe(I)Fe(0) charge-separated state that can react with a proton to generate Fe(I)Fe(II)·H, an intermediate for H2 production. As a result, a reaction vessel for the photocatalytic H2 production in an aqueous solution is established