Assessing the Effect of the Electron‐Beam Irradiation on Pd/Ga₂O₃ Catalyst under Ambient Pressure

Abstract

Introducing atmosphere in transmission electron microscope enables to directly observe the structural features of catalyst under working conditions. It offers the possibility to study the microstructural evolution and correlate real structures with catalytic properties at nano‐ or atomic‐scale during catalysis. However, the damages to catalyst derived from the high energy electron‐beam irradiation cannot be ignored and may lead to ambiguous conclusions, as the interaction between reactive gas molecules and active structures is only desired. Herein, the α‐Ga2O3 supported Pd catalyst was selected as a model to evaluate the potential effect of electron‐beam on the surface and interface structures, which directly affect the catalytic performance, at varied atmospheres, elevated temperatures and increased electron dose rate in ambient pressure. The results indicate that the supported Pd nanoparticles could be encapsulated by GaOx layer when the imaging electron dose rate is higher than 100 e/Å2s under reduction and oxidizing atmosphere. Either increasing the electron dose rate or elevating the temperature exacerbates the irradiation damage to α‐Ga2O3 support. This work was expected to evaluate the effect of electron dose rate to supported catalysts under chemical environments, and provide guidance for the investigation of in‐situ transmission electron microscopy under ambient pressure.

Sinter Resistance and Activity Enhancement via a Facet-Dependent Metal–Support Interaction of Pd/ZnO Catalysts in CO Oxidation

“…In situ transmission electron microscopy (TEM) is a versatile technique for observing and understanding the dynamic behavior of catalysts in the chemical environment. − It enables real-time imaging of the microstructural evolution of catalysts under volatile reaction conditions at the atomic level and corelating the dynamic behavior of catalysts with performance, which is extremely crucial for the structural regulation of catalysts. − In particular, the investigation of the thermal stability of the catalysts under the distinct gas environments and elevated temperature conditions is beneficial to realize the controllable preparation of supported catalysts. , Li et al demonstrated the distinct sintering behaviors of Au/TiO 2 catalyst under different atmospheres via environmental TEM (ETEM) and provided the microstructural information on TiO 2 support . Yang et al revealed that Pt NPs supported on graphene oxide preferentially exposed the high-index facets under elevated temperatures, which results in the aggregation of NPs and provides the direct evidence for the thermal instability of the catalysts .…”

Patterning the consecutive Pd 3 to Pd 1 on Pd 2 Ga surface via temperature-promoted reactive metal-support interaction

“…Thus, the microstructural evolution of Pd 2 Ga was monitored through ETEM at elevated temperatures. Here, electron dose rate less than 300 e·Å 2 s −1 was adopted during the HRTEM observation to avoid the possible damage from the high-energy electron beam according to our previous studies ( 34 ). One identical NP located on the edge of supports was selected to elucidate the ongoing surface variation (fig.…”