Photosystem I-Based Biohybrid Photoelectrochemical Cell

Photosynthesis is the process by which Nature coordinates a tandem of protein complexes of impressive complexity that function to harness roughly 90TW of solar energy on a global scale. Advances in biochemistry and nanotechnology have provided tools to isolate and extract individual components of this process. Here we show how one of these components, Photosystem I (PSI), is incorporated into an electrochemical system to yield a stand-alone biohybrid photoelectrochemical cell that converts light energy into electrical energy. The fabrication of the cell, in which PSI complexes are assembled into a dense multilayer on the surface of the cell's cathode, is described. The cells were irradiated with various intensities of white light and the corresponding responses of a typical cell's chronoamperometric behavior and open circuit potential are reported. The relationship between these responses and the photocatalytic behavior of PSI complexes is described. In addition, we report surface analysis of Photosystem I monolayers by scanning electrochemical microscopy (SECM) in light and dark conditions. SECM allows the direct detection of the electrochemical current measured through the tip electrode produced by the reducing side of PSI by the tip electrode.