Facet‐Dependent Strain Determination in Electrochemically Synthetized Platinum Model Catalytic Nanoparticles

Abstract

Studying model nanoparticles is one approach to better understand the structural evolution of a catalyst during reactions. These nanoparticles feature well‐defined faceting, offering the possibility to extract structural information as a function of facet orientation and compare it to theoretical simulations. Using Bragg Coherent X‐ray Diffraction Imaging, the uniformity of electrochemically synthesized model catalysts is studied, here high‐index faceted tetrahexahedral (THH) platinum nanoparticles at ambient conditions. 3D images of an individual nanoparticle are obtained, assessing not only its shape but also the specific components of the displacement and strain fields both at the surface of the nanocrystal and inside. The study reveals structural diversity of shapes and defects, and shows that the THH platinum nanoparticles present strain build‐up close to facets and edges. A facet recognition algorithm is further applied to the imaged nanoparticles and provides facet‐dependent structural information for all measured nanoparticles. In the context of strain engineering for model catalysts, this study provides insight into the shape‐controlled synthesis of platinum nanoparticles with high‐index facets.

Unconventional High-Index Facet of Iridium Boosts Oxygen Evolution Reaction: How the Facet Matters

“…This notion may be a result of the surfacestructure-dependent ligand and/or strain effects. 50,51 This notion theoretically explains that why a better OER behavior could be expected over the high-index Ir surface.…”

“…In our case, theoretical overpotential and Δ G O – Δ G OH have been well-balanced over the high-index (331) facet of Ir, with the position closest to the top of the volcano. This notion may be a result of the surface-structure-dependent ligand and/or strain effects. , This notion theoretically explains that why a better OER behavior could be expected over the high-index Ir surface.…”

“…14,28,30,35,50 However, the different improvements in OER activity for Pd@ Ir TOH, Pd@Ir cube, and Pd@Ir oct imply the facetdependent ligand and/or strain effects. 50,51 Particularly, such effects would be amplified over the high-index surface as a result of the introduction of atomic steps and kinks with low coordination numbers in high densities. Additionally, the corresponding Tafel plots were investigated to get more insight into their OER kinetics (Figure 3d and Figure S13).…”

“…Notably, the mass activities of Pd@Ir TOH/C, Pd@Ir cubes/C, and Pd@Ir oct/C were about 4.7-, 3.8-, and 1.2-fold relative to that of commercial Ir/C, respectively. It should be noted that the possible ligand and/or strain effects arising from the Pd core underlying the Ir surface should make contribution to the concomitant enhancement of OER activity, akin to the other bimetallic core–shell nanocrystals. ,,,, However, the different improvements in OER activity for Pd@Ir TOH, Pd@Ir cube, and Pd@Ir oct imply the facet-dependent ligand and/or strain effects. , Particularly, such effects would be amplified over the high-index surface as a result of the introduction of atomic steps and kinks with low coordination numbers in high densities. Additionally, the corresponding Tafel plots were investigated to get more insight into their OER kinetics (Figure d and Figure S13).…”

Effects of Platinum Nanoparticles on Rice Seedlings (Oryza sativa L.): Size-dependent Accumulation, Transformation, and Ionomic Influence

“…Platinum nanoparticles (PtNPs) are widely used in automotive catalysts, biomedical devices, jewelry, electrical, and glass industries. 1,2 Pt is a noble metal element with low concentrations in unpolluted environments. 3,4 However, Pt content is increasing in soils, rivers, and oceanic environments, usually as elementary nanocrystalline Pt attached to other metal particles.…”