Title
FRET guided surging of cyanobacterial photosystems improves and stabilizes current in photosynthetic microbial fuel cell
Author
Sharbani Kaushik, Mrinal K Sarma, Pranab Goswami
Year
2017
Journal
Journal of Materials Chemistry A
Abstract
Improving power generation under low light condition and capturing electrons efficiently from the photosynthetic bacteria on the electrode are critical issues for developing a viable photosynthetic microbial fuel cell (PMFC). To address these issues, an anode has been developed for a dual chambered PMFC with an abiotic cathode, by casting a nanocomposite matrix comprising of CdTe quantum dots (QD), graphene nanoplatelets (GNP) and silk-fibroin (SF) on graphite electrode. The nanocomposite matrix supported biofilm growth of the photo-catalyst Synechococcus sp., surged the bacterial photosystems (PS I and PS II) with appropriate light (λ650-750 nm) at a broad excitation spectrum (λ350-644 nm) through fluorescence resonance energy transfer and facilitated the metabolic electron relay through direct electron transfer (DET) to the anode. The maximum current density of the PMFC obtained with the nanocomposite bioanode (1.89 A m-2) was ~5.7 fold higher than the corresponding blank graphite anode. The positive effect of QD was further confirmed from the fading reversal of polarity during the circadian cycle leading to sustain current generation in the PMFC. The GNP reduced the band gap of the nanocomposite to 2.9 eV, and decreased the charge transfer resistance by ~ 9 fold thus, enabling DET on the electrode as evident from a pair of redox peak of the bioanode with a formal potential of -156 mV. Structural studies demonstrated rational interactions of the hydrophobic β-sheet of the SF with the nanomaterials. An unprecedented light conversion efficiency of 4.01 % for the cyanobacteria was achieved with the nanocomposite bioanode based PMFC.
Instrument
J-815
Keywords
Circular dichroism, Secondary structure, Ligand binding, Nanostructures, Biochemistry, Materials