Electrochemical Analysis and Scanning Electrochemical Microscopy Investigations of Photosystem I

Abstract

The increase in demand for energy has made Photosystem I (PSI), which can convert solar energy into a charge separation with an incredible efficiency, a topic of great research interest. By analyzing the PSI energy conversion process using electrochemical analytical methods, the natural inspiration for the solar energy conversion ability of bio-hybrid electrodes has been explored. In this study, various redox mediators were investigated to facilitate electron transfer in PSI-based systems. The analysis offered a novel perspective on how mediators impact the photocurrent generation, indicating that relative energy between mediators and enzyme cofactors, as well as light absorbance interference, are key factors to be considered while choosing an appropriate mediator for a photo-electrochemical system. This thorough study of mediators facilitates PSI based applications. Secondly, the light induced reduction-oxidation process in a PSI bio-hybrid electrode has been probed by scanning electrochemical microscopy (SECM). The first simultaneous amperometric photocatalytic responses both above and below a PSI film have been observed. The approach curve results reveal that film of PSI serves as an effective blocking insulator under dark conditions; however, the PSI films were able to regenerate redox species with limiting kinetics under illumination. Finally, multilayer films of PSI have been used to photoreduce platinum particles on the photoactive biofilm. SECM experiments were used to demonstrate the catalytic ability of these particles for the H+/H2 redox couple. These works explored the photo-electrochemical behavior of PSI multilayer films and broadened the application of SECM in the biological and renewable energy fields. They provide insights for utilization of natural materials in bio-hybrid devices to meet our energy demands.