Tuning the Electronic and Molecular Structures of Bioinspired Heterodinuclear NiFe Catalyst for Enhanced Catalytic H₂ Evolution

This is the authors' abstract. We don't add key points for this paper.

High Resolution Image Download MS PowerPoint Slide With the aim of enhancing the HER activity of the previously described bioinspired [NiFe]-hydrogenase complex [L N2S2 Ni II Fe II Cp(CO)] + ( LNiFe, with L N2S2 = 2,2′-(2,2′-bipyridine-6,6′-diyl)bis(1,1′-diphenylethanethiolate) and Cp = cyclopentadienyl), the electronic structure of the L N2S2 site has been fine-tuned. In L OMe NiFe, the bipyridine (Bpy) unit was substituted with methoxy electron-donating groups, while in L Phen NiFe, the Bpy unit was replaced with the 1,10-phenanthroline backbone. These complexes were fully characterized, and their HER activity was investigated. A mechanistic study was conducted by using IR and EPR spectroscopies combined with density functional theory (DFT) calculations. Both complexes act as efficient electrocatalysts to produce H 2, following an ECEC mechanism, starting from the monoreduced species. L OMe NiFe exhibits the fastest kinetics among the series ( K obs = 1.6 × 10 4 s –1 ), attributed to its higher Δp K a value for the protonation step of the two-electron reduced species, [ L OMe NiFe] – . In contrast, L Phen NiFe exhibits the lowest overpotential, with a cathodic shift of 150 mV. This improved performance is attributed to the fact that the phenanthroline backbone is more easily reduced with respect to a bipyridine unit.