Characterization of Bioelectrochemical Fuel Cell Fabricated With Agriculture Wastes and Surface Modified Electrode Materials

Abstract

A bioelectrochemical fuel was fabricated with pretreated and fermented rice husks. The fuel was characterized with variation of process variables by determination of chemical oxygen demand (COD) which is a measure of the oxygen equivalent of electrochemically oxidizable organic fuel to produce electrical energy. The electrodes of the cell were made with nanoporous pure Al coated with platinum, platinum-ruthenium, and platinum-ruthenium-carbon. Anodization parameters were optimized by studying E-I characteristics in sulfuric and oxalic acids with variation of concentration and temperature. Pore size on the order of 30–50 nm was obtained by a two stage anodization. The performance of the cell was evaluated by determining open circuit potential, E-I characteristics, polarization studies, and cyclic voltammetry. A steady onload potential of 600–800 mV was obtained with current density on the order of 15–25 mA/cm2 . High power density of 10–15 mW/cm2 has been obtained with electrode materials coated with Pt + Ru or Pt + Ru + C. The performance of coating on nanoporous structure was greatly reflected in the polarization studies, which showed a huge reduction of polarization resistance and increase of exchange current density by many times, the effect being more for anode with anodic solution, fermented rice husk, than with cathode with phosphate buffer cathodic solution. The surface morphology examined by SEM, showed nanodeposits of Pt, Pt-Ru, and the presence of carbon like structure. XRD peaks clearly reveal presence of Pt, Pt-Ru, and carbon.