Activity, selectivity, and methanol tolerance of novel carbon-supported Pt and Pt3Me (Me = Ni, Co) cathode catalysts

Abstract

The activity, selectivity, and methanol tolerance of novel, carbon supported high-metal loading (40 wt.%) Pt/C and Pt 3 Me/C (Me = Ni, Co) catalysts for the O 2 reduction reaction (ORR) were evaluated in model studies under defined mass transport and diffusion conditions, by rotating (ring) disk and by differential electrochemical mass spectrometry. The catalysts were synthesized by the organometallic route, via deposition of pre-formed Pt and Pt 3 Me pre-cursors followed by their decomposition into metal nanoparticles. Characteristic properties such as particle sizes, particle composition and phase formation, and active surface area, were determined by transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. For comparison, commercial Pt/C catalysts (20 and 40 wt.%, ETek, Somerset, NJ, USA) were investigated as well, allowing to evaluate Pt loading effects and, by comparison with the pre-cursor-based catalyst with their much smaller particle sizes (1.7 nm diameter), also particle size effects.Kinetic parameters for the ORR were evaluated; the ORR activities of the bimetallic catalysts and of the synthesized Pt/C catalyst were comparable and similar to that of the high-loading commercial Pt/C catalyst; at typical cathode operation potentials H 2 O 2 formation is negligible for the synthesized catalysts. Due to their lower methanol oxidation activity the bimetallic catalysts show an improved methanol tolerance compared to the commercial Pt/C catalysts. The results indicate that the use of very small particle sizes is a possible way to achieve reasonably good ORR activities at an improved methanol tolerance at DMFC cathode relevant conditions.

Combinatorial Search for Quaternary Methanol Tolerant Oxygen Electro‐Reduction Catalyst

“…Most of the methanol tolerant ORR catalysts reported previously are binary systems such as PtCo [2,12], PtFe [7,16], RuSe [11,13,14], PtSe [10], Pd-M (M = transition metals) alloys [4,9] and IrCo [8]. Only few reports dealt with ternary compositions such as MoRuSe [6] and RuSeW [15].…”

Half‐Cell Investigations of Cathode Catalysts for PEM Fuel Cells: From Model Systems to High‐Surface‐Area Catalysts

“…Compensation schemes for the solution resistance (R u ) must be implemented. 4. The diffusion limit current of ORR should be within 10% of the theoretical value.…”

“…Alternatives are electrochemical flow cells [3,4] or microelectrode setups [5]. More recently the authors have devoted a considerable amount of time to improving measurement reproducibility of the ORR in a RDE configuration, and establishing benchmark activities.…”

Post-annealing Effects on Reaction Selectivity of Methanol Oxidation at Carbon-based Platinum Co-sputtered Electrocatalyst

“…9 This is because Pt-based electrocatalysts used in the DMFCs have high activities for both reactions of the methanol oxidation and O 2 reduction. 9,10 To address the problems of DMFCs, as mentioned above, electrocatalysts having reaction selectivity of O 2 reduction or methanol oxidation have been investigated. [11][12][13][14][15][16] Of them, we examined the reaction selectivity of methanol oxidation at Pt-based catalysts.…”