The Exceptional Tandem Catalyst Pt1Pd1 NPs Embedded on a Fe3O4-Polypyrrole Composite Serving in Both the Ethanol Oxidation Reaction and Oxygen Reduction Reaction in Direct Ethanol Fuel Cells

Abstract

The present study explores the contributory benefits of PtPd catalyst nanoparticles supported on a mixed valence iron oxide (Fe₃O₄) and polypyrrole (PPy) composite for validation in both the ethanol oxidation reaction and oxygen reduction reaction (ORR) in alkaline medium for low temperature direct ethanol fuel cells (DEFCs). The high electrochemical surface area (ECSA) for PtPd/PPy-Fe₃O₄ with smart intervention of Fe₃O₄ directly/indirectly in the EOR and ORR sequences makes this distinct catalyst a highly preferred choice in direct ethanol fuel cells with respect to reduced polarization loss, substantial current density output, and greater stability compared to the usual Pt or Pd single nanocatalysts supported over carbon, while the conducting polymer present in the composite matrix enhances the charge transfer ability within the direct ethanol fuel cell framework. The catalyst nanoparticles are found to be in the size range 4–5 nm, as revealed from structure and morphology studies. Ion chromatographic analysis quantifies the reaction intermediates, acetate and carbonate, to the extent of 366 and 251 ppm using 1 M ethanol solution, while a low yield of H₂O₂ is a testament to the major utility of the combinatorial approach in the ORR. The studies involved morphology determined through electron microscopy and electrochemical characterization with the help of potentiodynamic polarization and RDE-RRDE techniques. The catalytic preeminence of the nanostructured PtPd/PPy-Fe₃O₄ was manifested by the facile electrode kinetics at the anode and cathode, the low yield of H₂O₂ in the ORR, and the appreciable power density output of 47.65 mW/cm² of the complete cell bearing enormous mass activity for both the EOR and ORR. This novel attempt of introducing the single robust catalyst at both ends ensures better catalyst utilization, imparts affordability, and avoids carbon corrosion in the fuel cell environment.