Fabrication of supercapacitors based on cellulose nanocomposites for use in biological fuel cell

The aim of this Ph.D. thesis is to develop novel concepts of super-capacitive Microbial Fuel Cells (MFCs) by focusing on nanocomposite anodes and cathodes constructed from low-cost bacterial cellulose (BC), carbon materials, and conductive polymers. The use of BC, a biopolymer synthesized by some species of bacteria, as a porous media membrane for fabricating a capacitive membrane electrode assembly (MEA) in MFC was performed by a novel method. Binder-less coating of that side of BC, exposed to the air, with CNTs made a homogeneous coating by which the impedance of the MEA decreased noticeably. On the other side of BC, exposed to anolyte, Nano zycosil (NZ) coating could create a barrier to oxygen cross-over and prevent anolyte leakage. This monolithic MEA structure with a low expense of fabrication is introduced for the first time in this thesis. MFC performance in the presence of the cellulosic MEA compared with the GDE showed higher power density, lower internal resistance, higher catalytic activity, and higher capacitance. BC-based anodes demonstrated excellent capacitance. BC-CNT was covered with polyaniline (PANI) through pulse electro-polymerization in this work. CNTs and PANI as super-capacitive materials showed different capacitance trends vs. anodic biofilm formation. PANI as a biocompatible conductive polymer provided a better condition on BC-CNT-PANI anode for microbial colonization. The effect of PANI on the capacitive response of biofilm by impedance was studied for the first time. Finally, MFC performance was improved by short-circuiting BC-CNT to a high capacitance PANI-modified BC-CNT as an additional anode giving rise to enhancing double-layer capacitance of anode and thus higher apparent capacitance and power density of the cell.