Temperature Dependence of Oxygen Reduction Activity at Pt−Fe, Pt−Co, and Pt−Ni Alloy Electrodes

Abstract

Oxygen reduction reaction (ORR) activity and H(2)O(2) formation at Pt(54)Fe(46), Pt(68)Co(32), and Pt(63)Ni(37) electrodes in 0.1 M HClO(4) solution at 20 to 90 degrees C were investigated by using a channel flow double electrode method. In the temperature range of 20-50 degrees C, the apparent rate constants k(app) for ORR at these electrodes were found to be 2.4-4.0 times larger than that at a pure Pt electrode, whereas their apparent activation energies of 41 kJ mol(-1) at -0.525 V vs E degrees (0.760 V vs RHE at 30 degrees C) were comparable to that at the Pt electrode. H(2)O(2) yield was ca. 1.0% at Pt(54)Fe(46) and ca. 0.16% at Pt(68)Co(32) and Pt(63)Ni(37) between 0.3 and 1.0 V vs RHE. The k(app) values at the alloy electrodes decreased with elevating temperature above 60 degrees C, and settled to almost the same values at the Pt electrode. The H(2)O(2) production was not detected at the alloy electrodes once heated at the high temperature in the solution, probably due to the thickening of the Pt skin-layer by a considerable dissolution of nonprecious metal components (Fe, Co, Ni) from the alloys.

Oxygen Reduction Reaction Activity of Carbon-Supported Pt-Fe, Pt-Co, and Pt-Ni Alloys with Stabilized Pt-Skin Layers

“…4), P(H 2 O 2 ) increased at the Pt 2AL -Pt-M/C, particularly, at M = Fe. Such a tendency is similar to that observed for sputtered Pt-M alloy films, 24 and somewhat different from our catalysts (supported on different kinds of carbon materials) reported previously. 11,14 One of the possible reasons is that the Electrochemistry, 84(3), 133-137 (2016) P(H 2 O 2 ) may increase with increasing amounts of quinone-like oxide groups on the carbon surface, particularly formed at high potentials.…”

“…The j k values obtained at the Pt 2AL -PtCo/C and Pt 2AL -PtFe/C electrodes were nearly identical with that of Pt 2AL -PtCo/GCB. 16 The order of j k at Pt 2AL -Pt-M/C (Pt-Co μ Pt-Fe < Pt-Ni) is different from those of three sets of sputtered Pt-M alloys (Pt-Ni < Pt-Co < Pt-Fe), 1,24 Pt 50 M 50 /C (Pt-Ni μ Pt-Fe < Pt-Co), 9 and Pt 3 M/C (Pt-Fe < PtNi < Pt-Co). 25 The maximum enhancement factor in j k (compared with c-Pt/C) at Pt 2AL -PtNi/C (4.3 times) is larger than those of Pt 50 M 50 /C, 9 Pt 3 M/C, 25 and sputtered Pt-M. 24 It should be noted that we cannot simply compare these results, because the experimental conditions (alloy composition, particle size, temperature, and potential sweep rate) are quite different.…”

“…16 The order of j k at Pt 2AL -Pt-M/C (Pt-Co μ Pt-Fe < Pt-Ni) is different from those of three sets of sputtered Pt-M alloys (Pt-Ni < Pt-Co < Pt-Fe), 1,24 Pt 50 M 50 /C (Pt-Ni μ Pt-Fe < Pt-Co), 9 and Pt 3 M/C (Pt-Fe < PtNi < Pt-Co). 25 The maximum enhancement factor in j k (compared with c-Pt/C) at Pt 2AL -PtNi/C (4.3 times) is larger than those of Pt 50 M 50 /C, 9 Pt 3 M/C, 25 and sputtered Pt-M. 24 It should be noted that we cannot simply compare these results, because the experimental conditions (alloy composition, particle size, temperature, and potential sweep rate) are quite different. However, a careful comparison of the results of alloy nanoparticles with the identical evaluation conditions in our group 10,11,14,16 suggests an importance of the modified electronic structure of the Pt-skin layer from the underlying alloy, i.e., control of both the formation of a thin, uniform Pt-skin layer and the alloy composition.…”

Effect of Co2+ on oxygen reduction reaction catalyzed by Pt catalyst, and its implications for fuel cell contamination

“…In addition, because of their low cost, non-platinum catalysts based on non-noble metals such as Fe [28] and Co [29] are considered sustainable cathode ORR catalysts. However, a major drawback of these low-Pt and non-Pt catalysts is metal dissolution [30][31][32]. For example, for Pt-Co alloys or Co-based non-Pt catalysts, Co dissolution becomes a major issue in a PEM fuel cell operating environment.…”

Research and Development of Highly Active and Durable Electrocatalysts Based on Multilateral Analyses of Fuel Cell Reactions

“…[1][2][3][4] For PEFC anode and cathode catalysts, the activity and its degradation have been analyzed by multilateral techniques such as X-ray photoelectron spectroscopy combined with an electrochemical cell (EC-XPS), 2,[5][6][7][8] in situ Fourier-transform infrared spectroscopy (FTIR), [9][10][11][12][13][14][15][16][17][18][19][20][21][22] electrochemical quartz crystal microbalance (EQCM), [23][24][25][26] in situ scanning tunneling microscopy (STM), [27][28][29][30][31] in addition to conventional electrochemical measurements such as rotating disk electrode (RDE), [32][33][34] channel flow electrode (CFE), 21,35,36 and channel flow double electrode (CFDE) methods. [37][38][39][40][41][42] Based on these results, new practical catalysts have been synthesized. [43][44]…”