SUGARS AND SUGAR ALCOHOLS AS USED AS A FUEL, DIRECT LIQUID INJECTED FUEL CELLS, POTENTIAL CANDIDATES

Direct liquid fuel cells (DLFCs) provide a path toward carbon neutral power by converting biomass derived molecules directly to electricity without external reforming. This thesis evaluates four renewable fuels: xylitol, galactose, mannose, and arabinose, in alkaline anion exchange (AEM) and split pH cation exchange (CEM) configurations. Palladium black served as the anode catalyst and platinum black as the cathode. Three electrode studies established surface areas and oxidation kinetics; cyclic voltammetry in 1 M KOH showed xylitol oxidation onset at −0.4V. Chronoamperometry confirmed stable activity over thirty minutes, indicating minimal catalyst poisoning. Fuel cell tests at 60 °C followed. In the AEM setup, 0.5 M xylitol with 2 M KOH produced 110 mW cm⁻² and retained 92 % of its initial voltage during a three-hour constant current hold, outperforming xylose under identical conditions. Increasing hydroxide improved all fuels, but mass transport limits appeared above 2.0 M substrate. Split pH cells further enhanced performance: feeding 0.5 M xylitol in 2 M KOH to the anode and 3 % H₂O₂ in 1 M H₂SO₄ to the cathode yielded 175 mW cm⁻² with stable operation over four hours. Galactose, mannose, and arabinose achieved 95, 88, and 83 mW cm⁻² respectively in AEM mode after the same optimization These findings establish xylitol as a high performance, low volatility DLFC fuel and show that split pH operation can nearly double power density without catalyst loadings beyond palladium and platinum black. The study advances understanding of polyol electro oxidation and provides design guidelines for sugar-based fuels in portable and stationary DLFC systems.