Self-Assembling Peptide-Co-PPIX Complex Catalyzes Photocatalytic Hydrogen Evolution and Forms Hydrogels

The sustainable production of carbon-free fuels such as hydrogen is an important goal in the search for alternative energy sources. Herein, we report a peptide-based system for light-driven hydrogen evolution from water under neutral conditions. The M1 peptide is an ABC triblock polymer featuring two coiled-coil alpha-helical regions flanking a water-soluble, polyanionic, intrinsically disordered region. M1 formed a hydrogel at high concentrations upon binding to cobalt protoporphyrin IX. This process is driven by the terminal regions, which coordinate the metalloporphyrin through histidine residues and form helical oligomers interconnected by flexible, intrinsically disordered regions, resulting in network formation. Co-M1 catalyzes hydrogen production upon irradiation in the presence of a photosensitizer and a sacrificial electron donor; the activity of Co-M1 is eight times higher than that of free Co-PPIX.