Light-induced hydrogen production by photosystem I–Pt nanoparticle conjugates immobilized in porous glass plate nanopores

Abstract

In recent years, a number of light-induced hydrogen production systems composed of photosystem I (PSI) and hydrogen production catalysts (e.g. hydrogenases and Pt nanoparticles) have been reported. However, the utility of these systems under aerobic conditions is limited due to their poor stability in the presence of oxygen. The development of light-induced hydrogen production systems that work under aerobic conditions is, therefore, of great importance to establish artificial photosynthetic devices. Ideally, these systems should utilise water as an electron source, via water splitting by photosystem II (PSII). We report the construction of a novel light-induced hydrogen production system composed of PSI-platinum nanoparticle conjugates and cytochrome c 6 (cyt c 6) immobilised in nanoporous glass plates (PGP50, 50-nm pore diameter). PSI trimer (PSIt) from Thermosynechococcus elongatus and Pt nanoparticles (PtNPs) were conjugated via electrostatic interactions (PSIt-PtNP). PSIt-PtNP and cyt c 6 were spontaneously absorbed in nanopores of PGP50 without denaturation. Upon irradiation in the presence of ascorbate as a sacrificial electron donor, catalytic H2 evolution was observed for PSIt-PtNP immobilised in the pores of PGP50 (PSIt-PtNP/PGP50) under both anaerobic and aerobic conditions, indicating that an effective photoinduced electron transfer system had been established. PSIt-PtNP/PGP50 was found to exhibit improved oxygen resistivity over the homogeneous solution system consisting of PSIt-PtNP, cyt c 6, and ascorbate, suggesting that the PSIt-PtNP/PGP50 system could be a potential candidate for artificial photosynthetic systems. The distribution of the components, PSIt-PtNP and cyt c 6, in PGP50 was characterised to discuss the efficiency of light-induced hydrogen production.