Effect of Redox Mediator on the Photo-Induced Current of a Photosystem I Modified Electrode

Abstract

The increase in demand for energy has made Photosystem I (PSI), which can convert solar energy into a charge separation with an efficiency near unity, a topic of great research interest. Redox mediators play an important role in the optimization of PSI based electrode systems. Profound understanding about how these mediators impact the photo-induced current of these bio-hybrid systems is necessary. Here we report the investigation of various mediators with formal potentials (E 0) that span the two electron transfer (ET) sites of PSI (E 0 from 0.48 to −0.65 V vs. Ag/AgCl). The present results have demonstrated that mediators with more positive formal potentials produced larger photocurrents. Ferricyanide was found to be the most effective mediator in this system at equilibrium potential, with a photocurrent density of 900 nA/cm 2. Additionally, the effects of the mediators' light absorbance and concentration properties have been studied. The mediators with light absorbance that overlap with the Qy band were found to have a more significant effect on photocurrent generation than mediators with absorbance overlap with the Soret band. This thorough study of these mediators facilitates PSI based applications, and offers a method to optimize bio-circuit devices that involve redox mediators.

Photobioelectrochemistry: Solar Energy Conversion and Biofuel Production with Photosynthetic Catalysts

“…66 The Cliffel research group has done extensive studies on photocurrent production with PSI electrodes. [67][68][69][70][71] Initially they immobilized PSI onto Au electrode surfaces using a SAM with terminal hydroxyl groups. However, this electrode only generated photocurrents of ∼7 nA/cm 2 with methyl viologen in solution as the electron acceptor.…”

Photosystem I Multilayers within Porous Indium Tin Oxide Cathodes Enhance Mediated Electron Transfer

“…Multilayers of PSI within pores can be expected to undergo mediated photocurrent production; therefore, they may surpass the pore size limitation of previous monolayer studies. Many electrochemical mediators have been studied within PSI bioelectrodes to achieve high rates of MET . One particularly high‐performing mediator pair is 2,6‐dichlorophenolindophenol (DCPIP) and ascorbate (AscH) .…”

“…Many electrochemical mediators have been studied within PSI bioelectrodes to achieve high rates of MET. [37,38] One particularly high-performing mediator pair is 2,6-dichlorophenolindophenol (DCPIP) and ascorbate (AscH). [10,37] Upon dissolution of sodium ascorbate salt into deionized water, AscH is protonated, forming ascorbic acid (AscH 2 ).…”

Modelling of the cathodic and anodic photocurrents from Rhodobacter sphaeroides reaction centres immobilized on titanium dioxide

“…Bacterial RCs and other photosynthetic proteins such as Photosystem I (PSI) have been tested in a variety of prototype photovoltaic devices (Lu et al 2007 ; Nagy et al 2010 ). Substrates employed have typically been flat metal surfaces (Ciesielski et al 2010 ; den Hollander et al 2011 ; Chen et al 2013 ; Swainsbury et al 2014 ), or alternatively flat (Tan et al 2012a , b ; Caterino et al 2015 ) or porous (Lu et al 2005b , a ; Lukashev et al 2007 ; Nadtochenko et al 2008 ; Woronowicz et al 2012 ; Mershin et al 2012 ; Nikandrov et al 2012 ; Gizzie et al 2015b ; Shah et al 2015 ; Yu et al 2015 ; Kavadiya et al 2016 ) semiconductor layers. A porous semiconductor film provides an up to 2000-fold higher surface area than that can be achieved with a planar electrode of the same 2-D area (O’Regan and Grätzel 1991 ) and materials such as TiO 2 are much cheaper than the precious metals such as gold and platinum commonly used for planar electrodes.…”