Improving the Ethanol Oxidation Activity of Pt-Mn Alloys through the Use of Additives during Deposition

Abstract

Abstract:In this work, sodium citrate (SC) was used as an additive to control the particle size and dispersion of Pt-Mn alloy nanoparticles deposited on a carbon support. SC was chosen, since it was the only additive tested that did not prevent Mn from co-depositing with Pt. The influence of solution pH during deposition and post-deposition heat treatment on the physical and electrochemical properties of the Pt-Mn alloy was examined. It was determined that careful control over pH is required, since above a pH of four, metal deposition was suppressed. Below pH 4, the presence of sodium citrate reduced the particle size and improved the particle dispersion. This also resulted in larger electrochemically-active surface areas and greater activity towards the ethanol oxidation reaction (EOR). Heat treatment of catalysts prepared using the SC additive led to a significant enhancement in EOR activity, eclipsing the highest activity of our best Pt-Mn/C prepared in the absence of SC. XRD studies verified the formation of the Pt-Mn intermetallic phase upon heat treatment. Furthermore, transmission electron microscopy studies revealed that catalysts prepared using the SC additive were more resistant to particle size growth during heat treatment.

Effect of Atomic Ordering on the Activity for Methanol and Formic Acid Oxidation of Pt‐Based Electrocatalysts

“…The comparison of the SA for methanol and formic acid oxidation of ordered and disordered Pt 3 M, PtM (M = first and second row transition metal), and PtCu 3 catalysts indicated that the SA of the ordered structures was higher than that of the disordered ones. A higher catalytic activity of Pt‐based intermetallic catalysts than that of the corresponding random alloys was also observed in the case of ethanol oxidation . The higher MOR activity of ordered catalysts than the disordered ones should be ascribed to the increased number of “good” sites for the MOR.…”

“…A higher catalytic activity of Pt-based intermetallic catalysts than that of the corresponding random alloys was also observed in the case of ethanol oxidation. [29,[67][68][69] The higher MOR activity of ordered catalysts than the disordered ones should be ascribed to the increased number of "good" sites for the MOR. Indeed, both the bifunctional mechanism and electronic effects required the presence of Pt and M sites close enough together, and the intermetallic compounds, with their regular repeating array of surface atoms, unlikely random site occupancy of alloys, would ensure the availability of the "good" sites in whole catalyst surface.…”

Electrocatalysis in Fuel Cells

“…PdW alloys [37] and hollow PdCu nanocubes [38], as well as PtMn alloys [39], showed some improvement over pure Pd or Pt toward EOR.…”

Ethanol Electrooxidation at Platinum-Rare Earth (RE = Ce, Sm, Ho, Dy) Binary Alloys

“…The advantage of alloy structures is no longer required to be proven, with numerous binary structure already tested; for example, Pt-M, with M = W, Pd, Rh, Re, Mo, Ti, Ce, Mn, Ni, and Cu always demonstrating a higher EOR activity than pure Pt as an anode catalyst [48,[67][68][69][70][71][72][73][74].…”