The Development of Biophotovoltaic Systems for Power Generation and Biological Analysis

Abstract

Biophotovoltaic systems (BPVs) resemble microbial fuel cells, but utilise oxygenic photosynthetic microorganisms associated with an anode to generate an extracellular electrical current, which is stimulated by illumination. Study and exploitation of BPVs have come a long way over the last few decades, having benefited from several generations of electrode development and improvements in wiring schemes. Power densities of up to 0.5 W m À 2 and the powering of small electrical devices such as a digital clock have been reported. Improvements in standardisation have meant that this biophotoelectrochemical phenomenon can be further exploited to address biological questions relating to the organisms. Here, we aim to provide both biologists and electrochemists with a review of the progress of BPV development with a focus on biological materials, electrode design and interfacial wiring considerations, and propose steps for driving the field forward.[a] L.

A biophotoelectrochemical approach to unravelling the role of cyanobacterial cell structures in exoelectrogenesis

“…For example, not all studies report the growth phase, which may affect exoelectrogenesis. 6,33 To investigate exoelectrogenesis at different phases in the growth cycle of cyanobacteria, we compared the photoelectrochemistry of cultures of the widely used cyanobacterial species Synechocystis at different growth phases: exponential (optical density at 750 nm 0.4), early stationary (OD750 = 1), and late stationary (OD750 > 1.5) phase. 34 Under the conditions described above, the cells at the different growth phases gave reproducible photocurrent profiles that were complex (i.e.…”

“…5 Despite our lack of understanding of the mechanism, exoelectrogenesis has been demonstrated to be useful for solar energy conversion applications, for example in biophotovoltaics where exoelectrogenic photosynthetic cells are employed to convert sunlight into electricity. [6][7][8][9][10] However, gaps in understanding of the mechanism(s) of exoelectrogenesis hinder the development of such novel biotechnologies.…”

Type IV Pili-Independent Photocurrent Production by the Cyanobacterium Synechocystis sp. PCC 6803

“…Current production in BPVs containing Synechocystis is largely dependent on illumination, and previous studies employing chemical and genetic inhibition indicate that water splitting by Photosystem II (PSII) provides the majority of electrons ( Bombelli et al, 2011 ; Pisciotta et al, 2011 ; Cereda et al, 2014 ). Improvements of BPVs based on advances in device architecture, electrode material, proton exchange membrane and use of mediators and biofilms have been reported ( Thorne et al, 2011 ; Bombelli et al, 2012 , 2015 ; Call et al, 2017 ; Rowden et al, 2018 ; Wenzel et al, 2018 ; Wey et al, 2019 ), but improvements arising from engineering of phototrophs have been limited to genetic removal of competing electron sinks ( Bradley et al, 2013 ; McCormick et al, 2013 ; Saar et al, 2018 ) by lack of understanding of how photosynthetic electrons are transferred from the photosynthetic apparatus to extracellular acceptors.…”

Enhanced Biophotocurrent Generation in Living Photosynthetic Optical Resonator

“…Biological photovoltaics (BPVs) are a developing technology that uses the natural process of photosynthesis in organisms to generate electricity. [2,[4][5][6][7][8][9][10] However, extracting bioelectricity from living photosynthetic organisms such as microalgae remains challenging. The greatest challenge originates from the extremely low transition rate from light to electricity, presumably due to the shielding by membrane systems from chloroplasts.…”