Degradation of polycrystalline rhodium and rhodium nanoparticles

Time and potential resolved dissolution analysis of rhodium using a microelectrochemical flow cell coupled to an ICP-MS

“…The current density for surface oxide formation between 0.8 and 1.2 V SHE ranges between 80 and 110 lA cm À2 , which is in good agreement with values obtained with the RDE at identical scan rates [23] and by other authors [12,16], assuming a proportional relation between oxide formation current density and scan rate in the latter cases. The shift of the reduction peak towards more negative potentials at higher potential limits due to irreversible oxide formation is nicely represented by the dataset.…”

“…4 approximately 1.7% of a monolayer of Rh is lost. Considering a recent study using an RDE setup using an identical electrode material [23], where the conditions of one experimental series (potential cycling at 100 mV s À1 between 0.7 and 1.07 V RHE in 0.1 M sulfuric acid) nearly match the ones applied here, a mass loss of 4.9 ng cm À2 cycle À1 (2.2% of a ML) was found. This value compares fairly well with the data presented in this work; the slight variations between the RDE and the SFC can most likely be attributed to the different electrolyte flow rate and velocity profile, both affecting possible re-deposition processes during the negative cycle, besides the slight difference in the potential window.…”

“…The positive potential limit during continuous cycling strongly affects rhodium degradation as well [4,12,23]. In order to provide real time dissolution data for this observation, an experimental sequence was performed that covers increasing upper potential limits from 0.6 to 1.4 V SHE in 200 mV integrals.…”

Relationships between Atomic Level Surface Structure and Stability/Activity of Platinum Surface Atoms in Aqueous Environments

“…In earlier reports, the stability of surface atoms has been examined by monitoring the potential-dependent change in surface morphology, either by utilizing cycling voltammetry (CV) alone or by a combination of CVs and scanning tunneling microscopy (STM) − or surface X-ray scattering (SXS). − Although these approaches were successful in measuring oxide-induced changes in both the local structure of surface atoms (STM) and long-range roughening of well-defined single crystals (SXS), these methods were unable to provide any information about the corrosion of metal surface atomsa subject that is of great fundamental and technological importance. Very recently, however, the development of a scanning flow cell (SFC) coupled to an inductively coupled plasma mass spectrometer (ICP-MS) has enabled in situ measurements of the dissolution of polycrystalline metal electrodes. − By utilizing this method, it was possible to establish relationships between potential-dependent oxide formation in various environments ,,, (pH 1–13, presence of Cl – anions, and reactive atmospheres such as H 2 , O 2 , and CO) and the dissolution of the corresponding cations with high sensitivity (ca. 3 pg cm –2 s –1 ).…”

Effect of Surface Composition on Electrochemical Oxidation Reaction of Carbon Monoxide and Ethanol of PtxRh1−x Solid Solution Electrodes

“…So far, the EOR activity of PtRh alloy catalysts has been evaluated at potentials over 1.0 V vs. RHE [1,[20][21][22][23][24][25] that was higher than the potential of oxidative Rh dissolution (0.8 V vs. RHE) [28,29]. So, the surface composition of PtRh alloys must be changed during the EOR activity evaluation.…”