title: Elucidating the role of methyl viologen as a scavenger of photoactivated electrons from photosystem I under aerobic and anaerobic conditions.
abstract: We present detailed electrochemical investigations into the role of dissolved O2 in electrolyte solutions in scavenging photoactivated electrons from a uniform photosystem I (PS I) monolayer assembled on alkanethiolate SAM (self-assembled monolayer)/Au surfaces while using methyl viologen (MV(2+)) as the redox mediator. To this end, we report results for direct measurements of light induced photocurrent from uniform monolayer assemblies of PS I on C9 alkanethiolate SAM/Au surfaces. These measurements, apart from demonstrating the ability of dissolved O2 in the electrolyte medium to act as an electron scavenger, also reveal its essential role in driving the solution-phase methyl viologen to initiate light-induced directional electron transfer from an electron donor surface (Au) via surface assembled PS I trimers. Specifically, our systematic electrochemical measurements have revealed that the dissolved O2 in aqueous electrolyte solutions form a complex intermediate species with MV that plays the essential role in mediating redox pathways for unidirectional electron transfer processes. This critical insight into the redox-mediated electron transfer pathways allows for rational design of electron scavengers through systematic tuning of mediator combinations that promote such intermediate formation. Our current findings facilitate the incorporation of PS I-based bio-hybrid constructs as photo-anodes in future photoelectrochemical cells and bio-electronic devices.
authors.affiliation: Materials Research and Innovation Laboratory (MRAIL), Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN 37996, USA. bkhomami@utk.edu dmukherj@utk.edu and Sustainable Energy Education and Research Center (SEERC), University of Tennessee, Knoxville, TN 37996, USA.
authors.forename: Tyler
authors.initials: T
authors.lastname: Bennett
authors.affiliation: Materials Research and Innovation Laboratory (MRAIL), Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN 37996, USA. bkhomami@utk.edu dmukherj@utk.edu and Sustainable Energy Education and Research Center (SEERC), University of Tennessee, Knoxville, TN 37996, USA.
authors.forename: Hanieh
authors.initials: H
authors.lastname: Niroomand
authors.affiliation: Department of Mechanical, Aerospace and Biomedical Engineering, University of Tennessee, Knoxville, TN 37996, USA.
authors.forename: Ravi
authors.initials: R
authors.lastname: Pamu
authors.affiliation: Center for Nanophase Materials Sciences (CNMS), Oak Ridge National Laboratory (ORNL), Oak Ridge, TN 37831, USA.
authors.forename: Ilia
authors.initials: I
authors.lastname: Ivanov
authors.affiliation: Materials Research and Innovation Laboratory (MRAIL), Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN 37996, USA. bkhomami@utk.edu dmukherj@utk.edu and Sustainable Energy Education and Research Center (SEERC), University of Tennessee, Knoxville, TN 37996, USA and Department of Mechanical, Aerospace and Biomedical Engineering, University of Tennessee, Knoxville, TN 37996, USA.
authors.forename: Dibyendu
authors.initials: D
authors.lastname: Mukherjee
authors.affiliation: Materials Research and Innovation Laboratory (MRAIL), Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN 37996, USA. bkhomami@utk.edu dmukherj@utk.edu and Sustainable Energy Education and Research Center (SEERC), University of Tennessee, Knoxville, TN 37996, USA and Department of Mechanical, Aerospace and Biomedical Engineering, University of Tennessee, Knoxville, TN 37996, USA.
authors.forename: Bamin
authors.initials: B
authors.lastname: Khomami
mesh_terms: D000458:Cyanobacteria / Q000378:metabolism; D055664:Electrochemical Techniques; D004566:Electrodes; D004579:Electron Transport; D004583:Electrons; D006046:Gold / Q000737:chemistry; D008027:Light; D018625:Microscopy, Atomic Force; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry; D010269:Paraquat / Q000737:chemistry* / Q000378:metabolism; D045331:Photosystem I Protein Complex / Q000737:chemistry / Q000378:metabolism*; D013499:Surface Properties
chemical_list: D045331:Photosystem I Protein Complex; D006046:Gold; D010269:Paraquat; D010100:Oxygen