Utilizing Toray Paper as a Metal-Free, High Surface Area Electrode for Photosystem I-Driven Mediated Electron Transfer

One challenge in capitalizing on the affordability, sustainability, and accessibility of biohybrid solar energy conversion, including devices based on Photosystem I (PSI), is the identification of metal-free electrode materials to replace the inorganic substrates commonly found in solar cell development. Herein, commercially available Toray carbon paper (CP) is investigated as a high surface area, carbon electrode for the development of photoactive bioelectrodes consisting of PSI and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). Mediated anodic photocurrent is achieved at both PSI multilayer and PSI-polymer composite films on CP electrodes subjected to flame pretreatment. Film preparation is optimized by utilizing potential sweep voltammetry in place of potentiostatic conditions for polymerization. The optimized PSI-PEDOT:PSS films achieve a threefold increase in polymer growth under potential sweep conditions, quantified through net charge consumed during electropolymerization, resulting in a fourfold increase in photocurrent density (-53 vs -196 nA cm(-2)). The ability to prepare photoactive PSI-polymer films on metal-free CP electrodes opens the door to a rapidly scalable system for biohybrid energy production ultimately leading to more affordable, sustainable, and accessible energy.