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, Fe 3+ /Fe 2+ and VO 2 + /VO 2+ , acting as redox catalysts and charge carriers, were used in the anode and cathode flow tanks, respectively. The wheat straw was first oxidized by Fe 3+ in the anode tank at approximately 100 °C. The reduced Fe 2+ in the anode was used to construct a fuel cell with VO 2 + in the cathode. The VO 2 + ions were reduced to VO 2+ and regenerated to VO 2 + by oxygen oxidation. The wheat straw flow fuel cell showed a power output of 100 mW cm −2 . Mediated with liquid Fe 3+ carriers, the solid powder of wheat straw could be gradually degraded into low‐molecular‐weight organic molecules and even oxidized to CO 2 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.