Identifying a Real Catalyst of [NiFe]‐Hydrogenase Mimic for Exceptional H 2 Photogeneration

Inspired by the natural [NiFe]‐H 2 ase, we designed mimic 1 , (dppe)Ni(μ‐pdt)(μ‐Cl)Ru(CO) 2 Cl to realize effective H 2 evolution under photocatalytic conditions. However, a new species 2 was captured in the course of photo‐, electro‐, and chemo‐ one‐electron reduction. Experimental studies of in situ IR spectroscopy, EPR, NMR, X‐ray absorption spectroscopy, and DFT calculations corroborated a dimeric structure of 2 as a closed‐shell, symmetric structure with a Ru I center. The isolated dimer 2 showed the real catalytic role in photocatalysis with a benchmark turnover frequency (TOF) of 1936 h −1 for H 2 evolution, while mimic 1 worked as a pre‐catalyst and evolved H 2 only after being reduced to 2 . The remarkably catalytic activity and unique dimer structure of 2 operated in photocatalysis unveiled a broad research prospect in hydrogenases mimics for advanced H 2 evolution.