Hydrogen‐Producing Catalysts Based on Ferredoxin Scaffolds

Abstract Current attempts to transform our fossil fuel‐based society into a sustainable one involve learning from and employing the biochemistry of nature. The process of photosynthesis is exemplary for utilizing sunlight as a regenerative energy source. Enzymes like hydrogenases, which reduce protons to molecular hydrogen (H ₂ ) under ambient conditions, are model biocatalysts for generating sustainable, clean fuels. In green algae, photosynthesis and hydrogenases are coupled through ferredoxin, a small electron transfer protein. Here, it is shown that several plant‐type ferredoxins can interact with a chemically synthesized active site cofactor analog of [FeFe]‐hydrogenases in a way that allows comparably high H ₂ evolution rates. UV–vis and Fourier‐transform infrared spectroscopy indicate that the natural [2Fe‐2S] clusters of the ferredoxin hosts must be absent for a functional interaction of polypeptide and cofactor mimic and that the apo‐ferredoxins shield the H ₂ ‐producing cofactor from the solvent. The hybrid proteins exhibited higher O ₂ tolerance than natural [FeFe]‐hydrogenases and generated H ₂ in light‐dependent cascades based on photosystem I or the chemical photosensitizer proflavine. These features and the combination of natural hosts and cofactors might contribute to establishing sustainable light‐dependent H ₂ production systems.