Inspired by the molecular principles of natural photosynthesis, solar conversion technologies have emerged as a promising solution to provide not just green electricity, but also energy vectors in the form of solar fuels and chemicals. Directions taken include synthetic, biomolecular or biohybrid photoelectrochemical devices characterised by various degrees of integration. Implementation of the synthetic artificial photosynthetic systems (APS) is hampered by the necessity to apply harsh conditions for the catalysis in each half-cell to occur efficiently, photocorrosion of electrode materials, often-limited product selectivity and catalyst instability. Moreover, the best performing inorganic and molecular catalysts usually encompass rare/toxic elements, which precludes such APS systems from large-scale implementation. Therefore, the alternative field of biomolecular and biohybrid artificial photosynthesis has emerged by combining the biotic components, which have been evolutionary optimised in their photocatalytic performance, with non-toxic and cost-effective synthetic materials for selective production of target chemicals at ambient conditions.
In this lecture, I present the bottom-up rational design that can yield the increased solar conversion efficiency and stability in biomolecular systems based on the robust photoenzyme, photosystem I (PSI). The PSI biophotocatalyst in these devices is interfaced with various cost-efficient, transparent electrode materials for production of green electricity and fuel. I will show that the performance of PSI-based devices is greatly improved by tailoring the structure of the organic conductive interface to ensure the generation of unidirectional electron flow and minimisation of wasteful back reactions. Specifically, incorporating transitional metal redox centres together with plasmonic nanoparticles in the molecular interface significantly improves not only the light-harvesting functionality of the PSI photoenzyme but also increases its long-term photochemical stability and the overall photoconversion efficiency. Such rational design paves the way for generation of viable and sustainable biomolecular technologies for solar energy conversion into fuel and carbon-neutral chemicals.
Acknowledgements: Support from the Polish National Science Centre (Solar-driven chemistry 2 SUNCOCAT grant no. 2022/04/Y/ST4/00107) and the Horizon Europe Research and Innovation Programme (SUNGATE, GA 101122061) is greatly acknowledged.