An In situ TEM study of the surface oxidation of palladium nanocrystals assisted by electron irradiation

Abstract

The surface oxidation of palladium nanocrystals plays an important role in changing the active sites and subsequently influencing the catalytic reactivity. Such a microscopy study on surface oxidation, down to the atomic scale, is essential for understanding the structure-property correlations of palladium nanocrystal based catalysts. Herein, we present an in situ atomic scale study on the surface oxidation behavior of palladium nanocrystals, which is induced by electron beam irradiation under low oxygen partial pressure and at room temperature inside an environmental transmission electron microscope. We found that: (i) surface oxidation initially started at the edge sites with atomic steps or vertex sites, which served as active sites for oxidation; (ii) the oxidation reaction proceeded with a much faster rate on the {111} surface, indicating a certain crystallography preference; (iii) nanometer-sized palladium monoxide islands were formed on the surfaces eventually. The results from our in situ studies provide insightful knowledge, and will be of certain importance for the design of improved functional catalysts in future.

Oxidation behavior of cobalt nanoparticles studied by in situ environmental transmission electron microscopy

“…(2) The electron beam may have enhanced the diffusion of Co also through the knock-on effect [30], thus promoting oxidation. (3) Electron beam irradiation may have assisted the decomposition of O 2 into atomic oxygen, and thus enhanced oxidation [23,33,34]. The high-energy electrons directly induced the ionization and disassociation of molecular oxygen in the microscope column and on the NP surfaces.…”

Coalescence dynamics of size-selected gold clusters studied by time-resolved transmission electron microscopy

“…The e-beam driven phenomena are commonly observed in electron microscopy studies, particularly for nanomaterials, for example, ref. [9], Despite that, a recent work [10] suggests that an electron beam driven stochastic motion can be very useful to study the mechanism of thermal driven stochastic motion underpinning coalescence in catalytic particles. Here, we focus on those clusters that got closer and coalesced.…”

Partially Oxidized Palladium Nanodots for Enhanced Electrocatalytic Carbon Dioxide Reduction

“…The lattice fringes with a space of 0.264 nm can be assigned to the PdO (101) plane. This observation matches well with the result that the oxidation prefers to launch reactions at the edge sites on Pd (111) surface, which has been previously proved by a TEM study on the surface oxidation state of Pd . The components of these nanodots are identified as Pd (JCPDS 65‐2867) and PdO (JCPDS 06‐0515) by X‐ray diffraction (XRD) analysis (Figure c).…”

“…This observation matches well with the result that the oxidationp refers to launch reactions at the edge sites on Pd (111)s urface, which has been previously provedb yaT EM study on the surfaceo xidation state of Pd. [19] The components of these nanodots are identifieda sP d( JCPDS 65-2867)a nd PdO (JCPDS 06-0515)b y X-ray diffraction (XRD) analysis ( Figure 1c). The resultant catalyst is mainly composed of the Pd (111)facet with the presence of PdO (101) facet.…”