Emulating photosynthetic processes with light harvesting synthetic protein (maquette) assemblies on titanium dioxide

Abstract

The emulation of photosynthetic systems has been vigorously pursued for more than thirty years both to assist in the understanding of natural photosynthetic processes as well as for the development of solar-to-fuel systems. While the majority of research has involved the extraction and binding of natural photosynthetic systems to electrodes, there have been limited studies of the electrode immobilisation of synthetic light harvesting proteins. The main focus of this work was to recreate a simplified version of a protein-based, energy generating artificial “photosystem” comprised of an amphiphilic zinc metalloporphyrin (light harvesting unit) ligated to a de novo synthetic protein or maquette. This artificial construct, electrostatically attached to a mesoporous titanium dioxide surface on an FTO electrode, affords the most efficient input (light) – output (photocurrent) protein-based device reported to date. The beneficial effect of the protein can be seen in the improvement of photo voltage through reduction in recombination losses and a more efficient photocurrent generation from a smaller dye loading. This synthetic protein-based construct opens the way for the coupling of this photosystem to catalysts for the development of a whole new generation of biomimetic devices.