Photosystem I-Based Biohybrid Systems for Photoelectrochemical Catalysis

Photosynthesis is the process by which Nature coordinates a tandem of protein complexes of impressive complexity that function to harness staggering amounts of solar energy on a global scale. Advances in biochemistry and nanotechnology have provided tools to isolate and manipulate the individual components of this process, thus opening the door to a new class of highly functional and vastly abundant biological resources. Here we show how one of these components, Photosystem I (PSI), is incorporated into non-biological systems to photocatalyze electrochemical reactions that produce an electrical current. We demonstrate that this process can be enhanced by moving from flat electrodes to high surface area, nanoporous electrodes which accommodate more PSI complexes and thus produce larger photocurrents. We also describe the fabrication of stand-alone photoelectrochemical cells in which the functions of light absorption and charge separation are performed by PSI complexes that are assembled into a dense multilayer on the cell's cathode, and we report the performance of these cells under various intensities of white light.