Electrocatalytic Activity of Supported Au–Pt Nanoparticles for CO Oxidation and O2 Reduction in Alkaline Medium

Abstract

Various Pt-and Au-based nanocatalysts prepared by water-in-oil microemulsion method were used to study CO stripping and the oxygen reduction reaction in alkaline medium. It was shown that the particle size increases with the amount of gold in the bimetallic composition, which could be explained by rapid reduction kinetic of gold salt in comparison to that observed with platinum one. This results in the faster formation of nuclei followed by a more rapid growth of the particles. Geometric effects responsible for strong adsorption of CO on high content gold-platinum nanoparticles are discussed as well as the appearing special feature of gold during CO stripping experiments. The absence of a prepeak potential on Au 70 Pt 30 /C nanoparticles could be due to a very small amount of weakly adsorbed CO on the surface. A CO-adsorbed layer seems to be so stable and compact that it does not present a formation of "holes" involving a low decrease in repulsive interactions between CO molecules and a shift of the main oxidation peak towards positive potentials. Moreover, the modification of the strength of the Pt-OH bond due to the presence of gold was described as well as the high catalytic activity of gold-based nanoparticles toward the oxygen reduction reaction in 0.1 M NaOH.

Recent Advances in Carbon Supported Metal Nanoparticles Preparation for Oxygen Reduction Reaction in Low Temperature Fuel Cells

“…Almost the same value of the OCP and E1/2 were reached in 0.1 M NaOH. The important diffusion current density obtained herein and compared to that resulting in the w/o method can be assigned to the synthetic method, whereas the magnitude of the metal loading is almost two times lower [33,52]. One of the recurring themes in the FCs performance loss is the decrease of the ORR activity due to the active electrochemical surface area (ECSA) loss over the cycles [9,58,[167][168][169][170].…”

“…Here, two microemulsions are mixed together, one containing the precursor and the other, the reducing agent. Due to the physical and chemical properties of its different constituents, the colloidal solution is very sensitive to temperature and the synthesis is currently performed at room temperature (20-25 °C) [34,49,50,[52][53][54][55][56]. Current reducing agents are sodium borohydride (NaBH4), hydrazine (N2H4), gas hydrogen (H2) etc.…”

“…This poses a considerable challenge to the material science community, particularly when considering that for most catalyst systems, durability and high current density work together with the PGM content. Habrioux and co-workers used the same w/o method to design platinum-gold nanoalloys with improved electrocatalytic properties [52]. They managed to reduce the metal charge up to 40 wt% without a significant loss in catalytic activities.…”

“…They managed to reduce the metal charge up to 40 wt% without a significant loss in catalytic activities. Au is known to improve the Pt electrode durability by modifying the Pt-OH bond strength [52]. O2 reduction starts at ca.…”

Oxygen Electroreduction Catalyzed by Bilirubin Oxidase Does Not Release Hydrogen Peroxide

“…Several researchers have studied the kinetics of oxygen reduction reaction (ORR) on noble metal catalysts [1][2][3] or by enzymes [4,5]. Among the biocatalysts capable of catalyzing the reduction of oxygen, much attention has been paid to the multicopper oxidase BOD, which is considered as the most efficient enzyme at physiological pH [5][6][7].…”