Dissolution Mechanism of Platinum in Acidic Media

Abstract

The platinum solubility in a polymer electrolyte would be a key issue in order to improve and guarantee the durability of PEFCs. In this study, the platinum solubility has been determined in acidic electrolytes as a function of temperature and pH. The solubility was ca. 3 x 10-6 mol dm-3 at 25oC in 1 mol dm-3 of H2SO4, HClO4, and CF3SO3H under air, and increased with temperature and with the decrease in pH. The platinum solubility in oxygen was slightly larger than that in air. However, the solubility in nitrogen was much smaller than the mixtures. Based on these results, the dissolution of platinum in an acidic medium would follow an acidic dissolution mechanism.

Facile Solvent-Free Synthesis of Metal Thiophosphates and Their Examination as Hydrogen Evolution Electrocatalysts

“…Microprobe analysis of the NiPS 3 and FePS 3 electrode tips after CA experiments using the platinum CE shows M/P/S elements, but Pt, if present, is below detection limits (Supplementary Figure S10). The results of the platinum CE track well with other reports describing the possibility of platinum ion migration from platinum counter electrodes that can impact metal catalyst stability in fuel cells and apparent catalyst activity in HER, particularly under acidic conditions and in the presence of oxygen-rich environments [60][61][62][63]. Graphite working electrodes show a significant increase in HER activity over time when using a platinum CE [64].…”

Synchrotron-Based In Situ Characterization of Carbon-Supported Platinum and Platinum Monolayer Electrocatalysts

“…In the latter case, Pd oxidation is caused by the place-exchange process between O and Pt in MLs. In the regime over 1 V, the preferential Pd oxidation presumably prevents the oxidation of Pt MLs, and thus, it imparts a certain degree of cathodic protection for Pt MLs. , At 1.51 V, the percentage of the oxide formation in Pt MLs is 21%, which is 3.6 times smaller than that of Pt/C (76% in Figure b; see also Figure S9). On the other hand, at the same potential, the percentage of PdO in Pd cores is 15%, which corresponds to 34% of Pd atoms on the surface of Pd cores (assuming that Pd oxidation occurs exclusively through the place-exchange mechanism and the N s / N t is ca.…”

“…Membrane electrode assembly (MEA) tests of the Pt ML electrocatalysts also demonstrated exceptional long-term stability. , The atomic structure of the Pt ML /Pd/C electrocatalyst was examined using in situ EXAFS, and the formation of Pt MLs on Pd nanoparticle surfaces and the contraction in Pt–Pt distance were confirmed . The EXAFS analysis also demonstrated that the Pt ML structure was almost retained after 60 000 potential cycles in MEA tests . In situ XAS studies provide information only from the Pt ML atoms on the surface of the metal nanoparticles that participate in electrocatalytic reactions; thus, direct and unambiguous comparison between electronic/structural properties of a catalyst and its activity can be made.…”

“…The loss of Pt through PtO 2 dissolution decreases both the edge height and the intensity of white line above 1.9 V. It was reported that the solubility of PtO 2 is approximately 2.5 × 10 −7 M in 0.1 M HClO 4 at 25 °C, and it increases in proportion to the [H + ]. 36 A simple model using Nernst's approach is employed to calculate a proton concentration near the PtO 2 surface under the OER and carbon corrosion (Figure S7). The estimated [H + ] at 2.37 V is approximately 5 M, which is 50 times larger than the bulk concentration (0.1 M HClO 4 ), and thereby the dissolution of PtO 2 must be considerably enhanced.…”

“…20 The EXAFS analysis also demonstrated that the Pt ML structure was almost retained after 60 000 potential cycles in MEA tests. 36 In situ XAS studies provide information only from the Pt ML atoms on the surface of the metal nanoparticles that participate in electrocatalytic reactions; thus, direct and unambiguous comparison between electronic/structural properties of a catalyst and its activity can be made.…”