Unraveling Photo-Driven H2 Production with a Bio-Inspired NiFe Complex: Revealing an Unexpected Hydrogen Atom Source

Developing efficient photocatalytic systems for sustainable H2 production is a crucial step toward reducing dependence on fossil fuels. While extensive research over the past two decades has focused on bioinspired FeFe catalysts, NiFe-based systems remain largely unexplored. This study addresses that gap by introducing the first heterodinuclear NiFe complex capable of catalyzing H2 production under photoassisted conditions. The catalyst demonstrates remarkable performance, achieving a turnover frequency of 2750 h–1 and a turnover number of up to 41200. A comprehensive mechanistic investigation, supported by EPR and labeling experiments, reveals that the photodriven catalytic pathway differs from the electrocatalytic mechanism. Under photoassisted conditions, BIH not only serves as a sacrificial electron donor, but its oxidized form, BIH·+, also acts as a hydrogen atom donor, directly contributing to the high activity of this system. These findings highlight the dual role of BIH in photoassisted catalysis, extending beyond its specific application in H2 production to other reactions of interest, such as CO2 reduction.