A Mechanistic Study of Dissolution of Pt–Fe Binary Alloys in 0.5 M H₂SO₄Solution by Channel Flow Triple Electrode

Abstract

A channel flow triple electrode (CFTE) was applied for the in situ detection of Fe ions (Fe(II) and Fe(III)) and Pt ions (Pt(II) and Pt(IV)) dissolved from Pt-50at%Fe (Pt-50Fe) and Pt-25at%Fe (Pt-25Fe), under potential cycling in 0.5 M H 2 SO 4 at 298 K. These ions, dissolved from a Pt-Fe alloy working electrode set upstream in a channel, were simultaneously detected on two Au collector electrodes placed downstream by reducing or oxidizing their dissolved ions. When Pt-50Fe was potential-cycled between 0.05 and 1.4 V vs. standard hydrogen electrode, Fe dissolution was significantly enhanced in a double-layer (DL) charging region (0.25-0.85 V), probably owing to the surface diffusion of Pt atoms. In addition, the Fe dissolution was enhanced by Pt dissolution which takes place in a place-exchange potential region (1.2-1.4 V) and in the reduction potential of Pt oxides (0.9-0.5 V) in the cathodic scan. On the contrary, when Pt-25Fe was potential-cycled between 0.05 and 1.4 V, Fe dissolution was strongly suppressed by a Pt-enriched layer, especially in the potential region for the DL. The dissolution also depended on the upper limit of potential cycling (E U

Formation of Pt Skin Layer on Ordered and Disordered Pt-Co Alloys and Corrosion Resistance in Sulfuric Acid

“…The dissolution of alloying elements is an additional concern about Pt alloy catalysts [36,37]. Some studies on the dissolution of alloying elements from Pt alloy electrodes have indicated that the dissolution of Pt skin layers triggers the dissolution of the alloying elements [38][39][40]; the corrosion resistance of the Pt skin layer formed on Pt-Co contributes enormously to the durability of Pt-Co alloy catalysts under the PEFC-operating condition. However, the dissolution behavior of the Pt skin layer in the simulated PEFCoperating conditions remains unclear because the corrosion resistance of the Pt skin layer cannot be evaluated by durability tests using Pt-Co nanoparticles.…”

Dissolution and the Consequent Surface Enrichment of Platinum in Pt–Cu Binary Alloys under Potential Cycling

“…In our previous work, it was revealed that Pt surface diffusion and dissolution accelerated Fe dissolution from Pt-50Fe during potential cycling using CFME. 26 The dissolution mechanism of Pt-50Cu was probably similar to that of Pt-50Fe, and that Cu dissolution was not suppressed by the Ptenriched layer in the later stage of potential cycling.…”

“…Furthermore, the current of Pt-50Cu was smaller than that of Pt-50Fe and was somewhat similar to that of Pt-25Fe. 26 In other words, the Pt-Cu alloys exhibited higher durability compared to Pt-Fe alloys when the alloy composition was the same. These results are in line with those in our previous work.…”

“…Recently, a novel system combining ICP-MS with a solution-flow system has been successfully established for the online and simultaneous detection of both Pt and M. [21][22][23][24] We also established a solution-flow electrochemical technique, known as channel flow multielectrode (CFME), for the detection of both Pt and Fe. 25,26 These techniques allowed us to obtain the dissolution profiles of both Pt and M under potential cycling and to consider the dissolution mechanism in detail. However, most of the previous work using these techniques mainly focused on the dissolution behavior of Pt-M alloys in their initial stage because of their experimental limitations.…”

Identical-Location Scanning Electron Microscopy Observation of Surface Morphological Changes of Pt–Cu Nanoparticles

“…Moreover, in order to clarify the dissolution behavior of PtM alloys in detail, a channel-flow multi-electrode (CFME) has been developed. 18,19) CFME can be used to provide information on the potential ranges and valences of Pt and Fe dissolved from PtFe alloys. Moreover, many researchers have attempted to develop online ICP-MS measurement systems with high detection sensitivities for dissolved ions and almost no limitation on the elements that can be analyzed.…”