Investigating the association between photosynthetic efficiency and generation of biophotoelectricity in autotrophic microbial fuel cells

Abstract

Microbial fuel cells operating with autotrophic microorganisms are known as biophotovoltaic devices. It represents a great opportunity for environmentally-friendly power generation using the energy of the sunlight. The efficiency of electricity generation in this novel system is however low. This is partially reflected by the poor understanding of the bioelectrochemical mechanisms behind the electron transfer from these microorganisms to the electrode surface. In this work, we propose a combination of electrochemical and fluorescence techniques, giving emphasis to the pulse amplitude modulation fluorescence. The combination of these two techniques allow us to obtain information that can assist in understanding the electrical response obtained from the generation of electricity through the intrinsic properties related to the photosynthetic efficiency that can be obtained from the fluorescence emitted. These were achieved quantitatively by means of observed changes in four photosynthetic parameters with the bioanode generating electricity. These are the maximum quantum yield (Fv/Fm), alpha (α), light saturation coefficient (Ek) and maximum rate of electron transfer (rETRm). The relationship between the increases in the current density collected by the bioanode to the decrease of the rETRm values in the photosynthetic pathway for the two microorganisms was also discussed.

Effect of different irradiance levels on bioelectricity generation from algal biophotovoltaic (BPV) devices

“…Hence, the SGR at 210 μmol photons m −2 s −1 was lower than the SGR at 90 μmol photons m −2 s −1 and 150 μmol photons m −2 s −1 , respectively (Figure 3). Ciniciato and collaborators 41 explained that the presence of electric field generated from the potential across an algal BPV cell could transform algal cell proteins and lipids and affect photosynthesis, reflected in terms of low F v /F m values. Once nutrient starts depleting, the cells enter stationary growth phase 48 and the effect of nutrient deficiency is revealed in terms of declining maximum quantum efficiency.…”

“…The minimum fluorescence value (F o ) during the dark adaption process and the maximum fluorescence value (F m ) when the reaction centers are closed after absorption of the energy of a photon were both measured with a PAM Fluorometer. 41 The variable fluorescence, F v , is the difference between F m and F o . The maximum quantum efficiency, F v /F m , can then be calculated with the following formula [5][6][7][8] :…”

Ruthenium oxide/tungsten oxide composite nanofibers as anode catalysts for the green energy generation of Chlorella vulgaris mediated biophotovoltaic cells

“…Where I p , n, and C 0 represent, respectively, the current maximum in amps, number of electrons participating in the redox reaction, and concentration of K 3 Fe(CN) 6 in supporting electrolyte. The area of electrode surface, diffusion coefficient, and sweep rate are denoted, respectively, as A (cm 2 ), D 0 (6.70 × 10 −6 cm 2 /s), and ν (V/s).…”

“…The inevitable depletion of fossil fuels and its combustion lead to deleterious effects on environment and global energy demand, which necessitates the prospective development of an efficient and sustainable green energy generation device, utilizing the renewable energy sources . Biophotovoltaic cell (BPV) has recently emerged as an influential green energy generation device, which efficiently converts light energy into electricity via the photolysis of water molecules with the aid of photosynthetic microbes (bacteria or microalgae) as biocatalysts . Among the different components in BPVs, anode is provided significant importance owing to its overall governance of fuel cell efficiency achieved via the adhesion of microalgae, metabolic water photolysis, and electron transfer .…”

“…[1][2][3] Biophotovoltaic cell (BPV) has recently emerged as an influential green energy generation device, which efficiently converts light energy into electricity via the photolysis of water molecules with the aid of photosynthetic microbes (bacteria or microalgae) as biocatalysts. [4][5][6] Among the different components in BPVs, anode is provided significant importance owing to its overall governance of fuel cell efficiency achieved via the adhesion of microalgae, metabolic water photolysis, and electron transfer. 7 Consequently, the exploration of robust and electroactive anode catalysts to improve the BPV performance is fundamentally logic.…”