Direct Conversion of Wheat Straw into Electricity with a Biomass Flow Fuel Cell Mediated by Two Redox Ion Pairs.

In this paper, a biomass flow fuel cell to directly convert wheat straw to electricity at low temperature (80-90 °C) and atmospheric pressure is presented. Two redox ion pairs, Fe3+ /Fe2+ and VO2+ /VO2+ , acting as redox catalysts and charge carriers, were used in the anode and cathode flow tanks, respectively. The wheat straw was first oxidized by Fe3+ in the anode tank at approximately 100 °C. The reduced Fe2+ in the anode was used to construct a fuel cell with VO2+ in the cathode. The VO2+ ions were reduced to VO2+ and regenerated to VO2+ by oxygen oxidation. The wheat straw flow fuel cell showed a power output of 100 mW cm-2 . Mediated with liquid Fe3+ carriers, the solid powder of wheat straw could be gradually degraded into low-molecular-weight organic molecules and even oxidized to CO2 at the anode without using noble-metal catalysts. The overpotential for the electrodes of the flow fuel cell was examined and the energy cost was estimated.