Cryo‐EM of Rationally Designed Photosystem I Nanoassembly on Graphene Validates Orientation‐Driven Enhancement of Photocatalytic Performance

Abstract Photosystem I (PSI)‐based photovoltaic performance is hampered by short‐circuiting and charge recombination between randomly oriented PSI complexes on the electrode surface. Various types of molecular interfaces have been designed to introduce control over the order of the PSI biophotocatalyst in the biomolecular nanodevices; yet, the precise orientation of the PSI complex has never been directly shown and quantified. Here, cryo‐electron microscopy (cryo‐EM) visualization of PSI particles following domain‐specific anchoring of this complex to the single‐layer graphene (SLG) is reported. By applying the rational design of the biomolecular interface, the preferential orientation of the PSI complex with its reducing side toward the SLG is directly demonstrated. This approach is effective to enhance anodic photocurrent generation three‐fold compared to the nanosystem with randomly deposited PSI particles. The cryo‐EM visualization of the PSI biomolecules on the graphene electrode surface provides the validation of the rational design of photocatalytic nanoarchitecture aimed at significantly improved photochemical performance.