In situ decoration of metallic catalysts in flow-through electrodes: Application of Fe/Pt/C for glycerol oxidation in a microfluidic fuel cell

Abstract

New multi-metallic materials have been synthesized to be used as active anodes in direct alcohol fuel cells. However, the separate steps of synthesis, characterization and preparation of the catalyst layer prior to their use are costly and time-consuming. Here, we propose a sustainable new method to in situ decorate catalysts with ad-atoms in flow-through porous electrode configuration. The ad-atoms are electrodeposited in a microfluidic fuel cell by driving the metallic precursor through the electrode under applied potential while blank electrolyte feeds the other half-cell porous electrode. Pt/C-modified carbon paper is decorated with Fe, which is subsequently used as an anode during operating the cell as a microfluidic direct glycerol fuel cell. The ultralow mass of Fe is calculated by integrating the reduction charge, in which the high residence time under controlled flow conditions increases the amount of Fe on Pt/C. The decoration can also be controlled by changing the concentration of the precursor, which is limited by the availability of Pt active sites. The power density of the obtained cell in flow-through porous electrode configuration is enhanced by 36% using the Fe-decorated anode, reaching ∼54 mW cm−2 at ∼0.7 V under mixed media conditions. Hence, the proposed method provides an effective means to modify, analyze and use bimetallic anodes at the same instrument and can be applied post-fabrication in any fuel cell or other flow cells with porous electrodes.