Electronic Thesis and Dissertation Repository


Master of Engineering Science


Chemical and Biochemical Engineering


Dimitre Karamanev


The BioGenerator as a fundamentally new type of H2-to-electricity conversion system offers a quite sustainable and cost effective solution to the challenges associated with the use of fuel cells in renewable power grids.The development of an anode electrode for the BioGenerator was subject of this work. The unique features of the BioGenerator require unique electrodes, and more specifically anode. The combination of biological cathodic liquid and the hydrogen gas fuel require specific hydrophobic/hydrophilic properties of the anode. Several different methods for anode formation were studied. The spreading technique was found to be most appropriate for the conditions in the BioGnerator. It was employed to fabricate three-layer hydrophobic PTFE-bound anode electrodes. The reproducibility, durability and performance stability of the mentioned electrodes were studied using i-V curves, ex-situ cyclic voltammetry, and through-plane gas permeability. In addition, the effect of hydrophobic polymer content (PTFE) in the backing substrates, including woven-fiber carbon cloth and nonwoven-fiber carbon papers, on the gas permeability, hydrophobicity, and long-term durability of anode electrodes was studied. Results showed that woven-fiber carbon cloth impregnated with 80-100 wt.% PTFE gives an enhanced durability towards flooding in the course of continuous operation at 100 mA cm-2. Moreover, causes of failure in the performance of the anode electrodes were assessed and results showed that the mass transfer is the main source of limitation in the long-term operation.