Revealing Elusive Intermediates of Platinum Cathodic Corrosion through DFT Simulations

Abstract

Cathodic corrosion of metals discovered more than 120 years ago remains a poorly understood electrochemical process. It is believed that the corrosion intermediates formed during cathodic polarization are extremely short-lived species because of their high reactivity. Together with the concurrent vigorous hydrogen evolution, this makes it challenging to investigate the reaction mechanism and detect the intermediates experimentally. From a computational standpoint, the process also presents a serious challenge as it occurs at rather low negative potentials in concentrated alkaline solutions. Here, we use density-functional-theory calculations to elucidate the identity of reaction intermediates and their reactivity at the Pt(111)/electrolyte interface. By controlling the electrode potential in an experimentally relevant region through constant Fermi-level molecular dynamics, we reveal the formation of alkali cation-stabilized Pt hydrides as intermediates of cathodic corrosion. The results also suggest that the found Pt anions could discharge at the interface to produce H 2 by reacting with either surface-bound hydrogen species or solution water molecules.

Corrosion of Electrochemical Energy Materials: Stability Analyses Beyond Pourbaix Diagrams

“…For instance, electrochemically driven incorporation of hydrogen into the bulk Pd nanocrystal is known to induce severe Pd lattice expansion causing a phase transition . In the case of Pt, which is one of the best catalysts for the hydrogen evolution reaction, surface Pt hydride structures of several monolayers may form thereby playing an important role in activity and cathodic corrosion of Pt. − This will introduce significant lattice strains that should cause surface reconstruction and eventual Pt detachment to solution. , …”

Pt nanoparticles under oxidizing conditions – implications of particle size, adsorption sites and oxygen coverage on stability

“…The positions of the atoms in the bottom layer in z direction have been kept fixed during relaxation performed using a Monkhorst-Pack k-point grid with (5, 5, 1) divisions. A similar slab model has been used elsewhere [48][49][50] .…”

“…A similar slab model has been used elsewhere. [48][49][50] Different PtO 2 nanoparticles have been constructed from the most stable b-PtO 2 bulk structure (orthorhombic, space group Pnnm) 51 following this procedure: (1) repeat the atoms in the primitive cell along all cell vectors; (2) remove Pt and O atoms that are the most distant from the structure centroid and have the lowest coordination numbers so that the number of dangling bonds is minimized and the stoichiometry of PtO 2 is maintained; (3) repeat step (2) until the target size is reached. By varying the parameters of the algorithm several different nanoparticles for each size have been obtained.…”

Metal deposition and electrocatalysis for elucidating structural changes of gold electrodes during cathodic corrosion

“…SHE). 19,28–32 For instance, Pt dissolution at moderate negative potentials during ORR in water and organic media was observed. 29,30 In highly-concentrated electrolytes such as 10 M NaOH, the cathodic corrosion of Pt starts already at −1.3 V vs .…”