Improvement of the Performance in Membraneless Aqueous H2O2 Fuel Cells By Electroadsorption of Ad-Anions on the Surface of the Cathodes

Abstract

Performance of a membraneless aqueous H2O2 fuel cells were significantly improved by assembling prussian blue-modified glassy carbon anodes (GC/PB) and gold cathodes whose surfaces were enriched by H2PO4 - ad-anions (Au/H2PO4 -). In this way, glassy carbon anodes were modified by a potentiostatically-deposited prussian blue (PB = Fe4[Fe(CN)6)]3•xH2O) film, whereas H2PO4 - ad-anions were electroadsorbed on the polycrystalline gold cathodes by means of cyclic voltammetry. The as-prepared electrodes were inserted in H2O2 fuel cells filled by deoxygenated phosphates buffer solutions (PBS, pH 2) containing several initial H2O2 concentrations. A highest power performance of the electrode materials was found by comparing all the discharge curves (potential vs. current plots) obtained as a function of the initial H2O2 concentration fed to the cells. Effect of the gap between the electrodes over the fuel cells performance was previously explored and optimized. The tabulated results below, demonstrate that the performance achieved for the cells constructed in this work was significantly superior to the best performance reported for comparable H2O2 fuel cells. Thereafter, electrochemical impedance spectroscopy (EIS) and a Bisquert type electrical transmission line [2] (data not shown), were employed for better understanding how an optimized electron-transfer kinetics for the Au/H2PO4 - cathodes allowed improving to the fuel cells performance. Finally, our results demonstrated that, once the Au/H2PO4 - cathodes were inserted into the H2O2 fuel cells the fill factor and the maximal power density were improved with the aid of the establishment of a competition between the electrical and ionic conductivities occurring through the PB films at the Au/PB anodes. open-circuit potential (mV) maximal current density (mA/cm2) fill factor maximal power density (mW/cm2) This work 741±11 13.5±0.4 0.56±0.03 5.6±0.2 Ref. [1] 600 10 0.26 1.6