Light Induced H2 Evolution from a Biophotocathode Based on Photosystem 1 – Pt Nanoparticles Complexes Integrated in Solvated Redox Polymers Films B

We report on a biophotocathode based on photosystem 1 (PS1)–Pt nanoparticle complexes integrated in a redox hydrogel for photoelectrocatalytic H₂ evolution at low overpotential. A poly(vinyl)imidazole Os(bispyridine)₂Cl polymer serves as conducting matrix to shuttle the electrons from the electrode to the PS1-Pt complexes embedded within the hydrogel. Light induced charge separation at the PS1-Pt complexes results in the generation of photocurrents (4.8 ± 0.4 μA cm–²) when the biophotocathodes are exposed to anaerobic buffer solutions. Under these conditions, the protons are the sole possible electron acceptors, suggesting that the photocurrent generation is associated with H₂ evolution. Direct evidence for the latter process is provided by monitoring the H₂ production with a Pt microelectrode in scanning electrochemical microscopy configuration over the redox hydrogel film containing the PS1-Pt complexes under illumination.