In this study a simple, fast and effective surface modification method for enhanced biofilm formation, increased electron transfer rate and higher current density generation from microbial fuel cell (MFC) has been demonstrated. This method consists of partial oxidation of carbon felt material by UV/O 3 treatment. Results from the electrochemical studies performed suggest that Shewanella oneidensis MR-1 biofilm formation is favored on UV/O 3 treated carbon felt electrodes when subjected to an applied potential of The possibility to directly convert the energy of chemical bonds into electricity has been recognized as an alternative and effective approach for energy transformation. This quest has been embodied in electrochemical devices including batteries and fuel cells. Commonly used batteries and fuel cells employ inorganic catalysts and harmful, costly electrolytes. In order to overcome the limited reserve of noble metals usually used and avoid the use of harmful compounds, a new avenue of electrochemical systems has been developed. These new systems rely on bio-catalytic ability of enzymes and microorganisms in fuel cells.1 The latter has gained attention of researchers, government agencies and industry driven by, among other things, the potential for combining efficient wastewater purification with concomitant electricity production. This achievement will provide an opportunity for the development of portable, self-sustaining wastewater treatment units.The electrode material and its properties are a key component, determining the performance and cost of Microbial Fuel Cells (MFCs).2 Therefore, electrode design is one of the greatest challenges in making MFCs a cost-effective and scalable technology.3-8 Among the general requirements, such as good conductivity, chemical stability, mechanical strength, high surface area and low cost, anode materials should posses several key characteristics that will determine the rate of bacteria-electrode interactions. These are, but not limited to: i) high surface roughness; ii) biocompatibility; and iii) surface chemistry that enhances bacterial attachment and electron transfer. [9][10]

Bioelectrochemical systems (BESs) are interesting systems that combine electrochemical red-ox reaction with biological activity for generating electricity from organic compounds. In fact, the organic compounds are actually the fuel for the fuel cell in which bacteria on the anode degrade organic molecules and transfer the resulting electrons to the electrode surface. The electrons move through the external circuit generating useful electricity to power devices or sensors. At the cathode, an oxidant is reduced to complete the red-ox reaction. Generally oxygen is used due to its high potential and natural availability. Interestingly, it has been found that some bacteria, named exoelectrogens, are able to transfer electrons extracellularly to a solid support, generally called the anode electrode, if the substrate oxidation reaction occurs in absence of oxygen. The halfway potential represents the potential at which the electron transfer mechanism of an exoelectrogen is most favorable and thus outputs the most electricity. The more negative the halfway potential, the more energy can be produced. The goal of this project is to maximize microbial energy production considering different anode material-bacteria interactions. Carbonaceous-based materials are typically used as anode in BESs due to their simplicity, low-cost fabrication, high surface area, high mechanical strength, high chemical resistance to corrosion and biocompatibility. It has been shown previously that both surface chemistry and surface morphology can affect positively or negatively the bacteria attachment on a surface. Unfortunately, the electrical conductivity of carbonaceous materials is generally low compared to other materials and the durability is often negatively affected in long-term operation mainly due to material deterioration. Materials other than graphite have been proposed as suitable anode materials, but the effect of anode material on the underlying mechanism of extracellular electron transfer (EET) has not been yet addressed. Here, we measure electron transport properties of the model organism, Geobacter sulfurreducens, under turnover (with organic substrate) and nonturnover (without organic substrate) conditions, using an array of materials as working electrodes of an MFC (glassy carbon (GC), graphite (GR), gold (Au), platinum mesh (Pt), nickel (Ni) and indium tin oxide (ITO)). Experimentally, a 1L reactor that accommodates 6 working electrodes was used so all of the working electrodes could be tested under the same conditions with the same reference and counter electrodes. Ag/AgCl (3M KCl) was used as reference electrode while Pt was used as counter. Each material was used as a separate working electrode and connected to a single potentiostat (VMP3, Biologic, Inc., Knoxville, TN) channel.  The reactor was operated using a three-electrode configuration at a set anode potential of +0.3 V (vs. Ag/AgCl) to study each material at stable fixed potential, as opposed to a floating potential observed for MFC anodes. Preliminary electrochemical tests produced cyclic voltammograms (CV) of all the materials under turnover and nonturnover conditions that displayed differences in slope and in the difference between halfway potential and formal potential, indicating that different materials yielded different electrochemical responses (Figure 1). The observed differences suggest that the bacteria are either using different electrochemical pathways to perform EET or that the material being used as the working electrode is influencing the environment and therefore altering the formal potential. We are currently conducting chemical measurements to characterize the working electrode surfaces along with a detailed study of the Geobacterbiofilm colonization. Finally, we will establish a relationship between the halfway potential and extracellular electron transfer dependence on the surface to which the biofilm is attached.  Figure 1. Polarization of Geobacter sulfurreducens grown for 14 days on various materials [Preliminary Data] Figure 1

Herein we present methods for synthesizing monodisperse mesoporous silica particles and silica particles with bimodal porosity by templating with surfactant micelle and microemulsion phases. The fabrication of monodisperse mesoporous silica particles is based on the formation of well-defined equally sized emulsion droplets using a microfluidic approach. The droplets contain the silica precursor/surfactant solution and are suspended in hexadecane as the continuous oil phase. The solvent is then expelled from the droplets, leading to concentration and micellization of the surfactant. At the same time, the silica solidifies around the surfactant structures, forming equally sized mesoporous particles. We show that hierarchically bimodal porous structures can be obtained by templating silica microparticles with a specially designed surfactant micelle/microemulsion mixture. Oil, water, and surfactant liquid mixtures exhibit very complex phase behavior. Depending on the conditions, such mixtures give rise to highly organized structures. A proper selection of the type and concentration of surfactants determines the structuring at the nanoscale level. Tuning the phase state by adjusting the surfactant composition and concentration allows for the controlled design of a system where microemulsion droplets coexist with smaller surfactant micellar structures. The microemulsion droplet and micellar dimensions determine the two types of pore sizes.