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Chronoamperometric investigations with rotating disc electrodes (RDEs) were used to characterise the anodic half‐cell of yeast powered microbial fuel cells using methylene blue (MB) as a mediator. Both convection and mediator adsorption were shown to affect the anodic current. A microbe–mediator limited reaction model was developed and shown to agree well with the experimental data. A power density of ∼150 μW cm–2 was achieved in a full cell, which represented a significant increase from prior reports on yeast‐catalysed fuel cells. The increased power density was enabled by using high mediator concentrations and by controlling the mediator adsorption.

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The power densities of microbial fuel cells with yeast cells as the anode catalyst were significantly increased by immobilizing the yeast in electrically conductive alginate electrodes. The peak power densities measured as a function of the electrical conductivity of the immobilized electrodes show that although power increases with rising electrical conductivity, it tends to saturate beyond a certain point. Changing the pH of the anode compartment at that point seems to further increase the power density, suggesting that proton transport limitations and not electrical conductivity will limit the power density from electrically conductive immobilized anodes.

The rheological and structural characteristics of polyimides with enhanced melt flow have been investigated. The polyimides were based on 2,3,3 1 , 4 1 -biphenyltertracarboxylic dianhydride (PBDA) and a mixture of a diamine, 4,4 1 (1,4-phenylene-bismethylene) bisaniline (BAX) and a triamine, 1,3,5-Tris (4-aminophenoxybenzene), TAB, where the amount of TAB was 4 and 8%. Melt viscosities of these polymers suggest that they are processable by resin infusion methods. Although curing occurs through the phenylethynyl endcap, the steric and electronic differences of the three amines results in different cure kinetics and heterogeneous crosslinking. This is manifested in multiple T g values in the differential scanning calorimetry (DSC) scan of the cured samples. Rheological and DSC kinetic studies of the cure behavior indicate that the sample with 4% TAB cures more quickly than the system with 8% TAB and it has a lower activation energy (147 versus 185 kJ mole 21 ). Thermal gravimetric analysis (TGA) scans indicate that both TAB based samples are more thermally stable than PMR-15. The lower activation energy for 8% TAB , relative to 4% TAB (147.0 versus 170.2 kJ mole 21 ) suggests the additional branching present decreases the thermal stability.

A biomimetic method to mitigate marine biofouling using a pilot-whale-inspired sacrificial skin concept has been developed. We developed a method to form conformal, protective skins in situ underwater using a circulatory system. In addition, the materials chemistry was tuned such that the skin dissolves after a tunable stable period, removing any foulants that may have collected on it. Skin formation, stability and dissolution have been studied by forming skins on 6 inch square flat substrates and curved surfaces. Several different materials and material combinations were tested for their skin-forming ability. Rheology studies were conducted to determine the changes in viscosity of the materials upon exposure to seawater. The materials’ microstructure and composition were probed before and after seawater exposure. These experiments helped explain the mechanisms by which skin formation and dissolution occurs. Biofouling experiments consisted of culturing and growing the bacteria Pseudoalteromonas carrageenovora, a strain known to cause biofouling in marine environments. Efforts focused on determining experimental conditions necessary to achieve high levels of biofouling growth in the shortest amount of time. A large reduction in biofouling was demonstrated for surfaces protected by the sacrificial skin compared to identical unprotected surfaces, when high fouling pressure was generated using bacteria in artificial seawater.

Renewable alternatives to fossil hydrocarbons for energy generation are of general interest for a variety of political, economic, environmental, and practical reasons. In particular, energy from biomass has many advantages, including safety, sustainability, and the ability to be scavenged from native ecosystems or from waste streams. Microbial fuel cells (MFCs) can take advantage of microorganism metabolism to efficiently use sugar and other biomolecules as fuel, but are limited by low power densities. In contrast, direct alcohol fuel cells (DAFCs) take advantage of proton exchange membranes (PEMs) to generate electricity from alcohols at much higher power densities. Here, we investigate a novel bio-hybrid fuel cell design prepared using commercial off-the-shelf DAFCs. In the bio-hybrid fuel cells, biomass such as sugar is fermented by yeast to ethanol, which can be used to fuel a DAFC. A separation membrane between the fermentation and the DAFC is used to purify the fermentate while avoiding any parasitic power losses. However, shifting the DAFCs from pure alcohol-water solutions to filtered fermented media introduces complications related to how the starting materials, fermentation byproducts, and DAFC waste products affect both the fermentation and the long-term DAFC performance. This study examines the impact of separation membrane pore size, fermentation/fuel cell byproducts, alcohol and salt concentrations, and load resistance on fuel cell performance. Under optimized conditions, the performance obtained is comparable to that of a similar DAFC run with a pure alcohol-water mixture. Additionally, the modified DAFC can provide useable amounts of power for weeks.