Synthesis and Evaluation of PtNi Electrocatalysts for CO and Methanol Oxidation in Low Temperature Fuel Cells

Abstract

Pt(Ni)/C and PtRu(Ni)/C catalysts were synthesized by electroless deposition of Ni on a carbon dispersion followed by sequenced Pt deposition and spontaneous deposition of Ru species. The structural analyses of the catalysts with 88:12 and 98:2 Pt:Ni atomic ratios pointed out to the formation of small hexagonal Ni crystallites covered by thin cubic Pt surface structures with no evidence about PtNi alloy formation. The onset potentials for CO oxidation on Pt(Ni)/C and PtRu(Ni)/C were about 0.10 and 0.24 V more negative than those of Pt/C, thus indicating their better CO tolerance. The surface Ru species appeared to have the major effect by facilitating the CO removal by the bifunctional mechanism. The onset potential for the methanol oxidation reaction (MOR) of Pt(Ni)/C was about 0.15 V lower than that of Pt/C. The mass and specific activities together with the exchange current densities of the Pt(Ni)/C catalysts were also higher than those of Pt/C, making in evidence their higher activity in front of the MOR. The Tafel slopes for the MOR on Pt(Ni)/C suggested different reaction mechanism than on Pt/C. The electronic (ligand) effect of Ni on Pt was considered the main reason to explain the higher activity of Pt(Ni)/C in front of the CO oxidation and the MOR.

Boosting the Role of Ir in Mitigating Corrosion of Carbon Support by Alloying with Pt

“…Although carbon impurities can be removed from the Pt surface of Pt/C as well, the corrosion of the carbon support and the loss of Pt nanoparticles at the high potentials can offset the cleaning effect, resulting in a slight decrease of normalized ECSA during the first 1k cycles. Meanwhile, Pt 85 Ir 15 /C shows a shoulder CO oxidation peak after 1k cycles (Figure f), implying the formation of a Pt-enriched shell induced by potential cycling. − …”

Influence of PtCu/C Catalysts Composition on Electrochemical Characteristics of Polymer Electrolyte Fuel Cell and Properties of Proton Exchange Membrane

“…The highest ESA values were observed for sample S3 with the initial metal composition PtCu 1.3 and for the commercial Pt/C catalyst (Table 2). It is known that the determination of the ESA value by hydrogen adsorption/desorption may be less accurate for bimetallic electrocatalysts than for Pt/C one [24][25][26][27]. Generally, an additional technique is used to determine the active surface area by the carbon monoxide stripping method [28].…”

“…The activity of the obtained bimetallic catalysts in the ORR was estimated on the basis of the normalized linear sweep voltammetry (LSV) curves (Figure 3a). For all investigated It is known that the determination of the ESA value by hydrogen adsorption/desorption may be less accurate for bimetallic electrocatalysts than for Pt/C one [24][25][26][27]. Generally, an additional technique is used to determine the active surface area by the carbon monoxide stripping method [28].…”

“…To this end, the electrolyte was saturated with oxygen for one hour. The calculation of the kinetic current at a potential of 0.90 V (RHE) was carried out according to the Koutetsky-Levich equation [27,30]. The mass (I mass ) and specific (I sp ) activities were calculated by dividing the kinetic current by the mass of platinum on the electrode and by the determined ESA, respectively.…”

The ''rolling up'' effect of platinum layer obtained on nickel surface by interaction with solution of H2PtCl6 and its electrocatalytic properties in hydrogen evolution reaction during water electrolysis in alkaline medium

“…One would expect such 3D microstructures to have unique electrocatalytic properties, for example, in HER during water electrolysis. Previously, GRR with the participation of these reagents was studied, in particular, in articles [13,14] on the examples of nickel nanoparticles and nickel foam.…”