title: An iron-iron hydrogenase mimic with appended electron reservoir for efficient proton reduction in aqueous media.
abstract: The transition from a fossil-based economy to a hydrogen-based economy requires cheap and abundant, yet stable and efficient, hydrogen production catalysts. Nature shows the potential of iron-based catalysts such as the iron-iron hydrogenase (H2ase) enzyme, which catalyzes hydrogen evolution at rates similar to platinum with low overpotential. However, existing synthetic H2ase mimics generally suffer from low efficiency and oxygen sensitivity and generally operate in organic solvents. We report on a synthetic H2ase mimic that contains a redox-active phosphole ligand as an electron reservoir, a feature that is also crucial for the working of the natural enzyme. Using a combination of (spectro)electrochemistry and time-resolved infrared spectroscopy, we elucidate the unique redox behavior of the catalyst. We find that the electron reservoir actively partakes in the reduction of protons and that its electron-rich redox states are stabilized through ligand protonation. In dilute sulfuric acid, the catalyst has a turnover frequency of 7.0 × 10(4) s(-1) at an overpotential of 0.66 V. This catalyst is tolerant to the presence of oxygen, thereby paving the way for a new generation of synthetic H2ase mimics that combine the benefits of the enzyme with synthetic versatility and improved stability.
authors: Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, Amsterdam 1098 XH, Netherlands.
authors: René
authors: 0000-0002-4165-6239
authors: R
authors: Becker
authors: Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, Amsterdam 1098 XH, Netherlands.; Center for Nanotechnology (CeNTech) and Physikalisches Institut, Westfälische Wilhelms-Universität Münster, Münster 48149, Germany.
authors: Saeed
authors: S
authors: Amirjalayer
authors: Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, Amsterdam 1098 XH, Netherlands.
authors: Ping
authors: P
authors: Li
authors: Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, Amsterdam 1098 XH, Netherlands.
authors: Sander
authors: S
authors: Woutersen
authors: Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, Amsterdam 1098 XH, Netherlands.
authors: Joost N H
authors: JN
authors: Reek
mesh_terms: D002384:Catalysis; D020134:Catalytic Domain; D004563:Electrochemistry / Q000379:methods; D004583:Electrons; D006859:Hydrogen / Q000737:chemistry; D006864:Hydrogenase / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D007506:Iron-Sulfur Proteins / Q000737:chemistry*; D008024:Ligands; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry; D011522:Protons; D012997:Solvents / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D007506:Iron-Sulfur Proteins; D008024:Ligands; D011522:Protons; D012997:Solvents; D014867:Water; D006859:Hydrogen; D007501:Iron; C118830:iron hydrogenase; D006864:Hydrogenase; D010100:Oxygen
keywords: Physical sciences; chemistry; electron reservoir; ligands; proton reduction; synthetic H2ase