High performance yeast-based microbial fuel cells by surfactant-mediated gold nanoparticles grown atop a carbon felt anode

The behavior of gold nanoparticles grown atop a polyethyleneimine functionalized carbon felt substrate is explored for the first time. This green synthesis growth process utilizes surface-bound seeds and an exploration of the effect of a surfactant ligand mediator on the directional growth of the gold nanoparticles. Rough, irregularly shaped, and wide-spread gold nanoflower structures are developed from the seeds atop the hydrophilic functionalized carbon felt fibers through this process. Nanoparticle growth is acquired by the adaptation of a simple solution consisting of a gold salt reducer (L-ascorbic acid), nanoparticle initiator (chloroauric acid), and a strong ligand (4-mercaptobenzoic acid, MBA). Nanoparticle growth time and the concentration of the directional mediating surfactant MBA are varied to optimize the synthesis. The gold nanoparticle structures are examined through X-ray photoelectron spectroscopy and high-resolution scanning electron microscopy. Furthermore, the effects of attachment, biofilm formation, and coverage activity on the performance of a yeast-based microbial fuel cell are electrochemically evaluated. Results show both favorable and unfavorable conditions for yeast biofilm inhabitancy which are verified through electron microscopy, and a relationship between the surface chemical compositions, incomplete gold salt reduction, presence of residual sulphur, and effective yeast active-surface coverage on modified carbon felt is demonstrated. The best power density achieved was 2771 ± 569 mW·m⁻² for the polyethyleneimine-modified carbon felt with gold nanoparticles prepared with 715 μM MBA for 30 min; a value higher than many benchmarks referenced in literature representing a new contribution to the field.