| Although fuel cells are based on a concept dated more than 170 years ago, thorough and focused research did not take place in this field until the last five decades. Therefore, considering that fuel cells are the main candidates for portable power for the near future, there are questions that need to be answered and problems that need to be solved if wide applications of fuel cells are to be achieved. The research elaborated in this thesis was carried out to solve some of the problems and overcome some of the challenges. On the subject of Direct Formic Acid Fuel Cells, a search for a better and cheaper catalyst than those already known was conducted, and at the same time conditions for the Membrane Electrode Assembly preparation were explored. Concomitantly, the electrochemical reduction of carbon dioxide was investigated under conditions that primarily yield formic acid. The research was aimed at maximizing the efficiency as well as the rate of the carbon dioxide reduction.;One of the cathode reactions in fuel cells, which is the reduction of oxygen to water, is known to have sluggish kinetics relative to most of the fuel oxidation reactions. This is another key issue, where breakthroughs are important and there is still room for improvement. A catalyst based on Pt supported over carbon monofluoride (CFx) was prepared and tested in fuel cells cathodes using hydrogen and methanol as fuels. In addition to the fuel cell performance with the new cathodic catalyst, electrochemical properties of the catalyst were also investigated.;The final part of the present thesis is related to microbial fuel cells. These types of fuel cells have been developed in the last decade. For this reason, the different components of the fuel cell and the assembly procedures have neither been standardized nor their performances maximized. Therefore, the research was aimed to test different materials for the fuel cell fabrication as well as to standardize assembly procedures, while at the same time improving the power output by application of all the advances that have taken place in chemical fuel cells. |
