Visualizing Gas Molecules Interacting with Supported Nanoparticulate Catalysts at Reaction Conditions

Abstract

Understanding how molecules can restructure the surfaces of heterogeneous catalysts under reaction conditions requires methods that can visualize atoms in real space and time. We applied a newly developed aberration-corrected environmental transmission electron microscopy to show that adsorbed carbon monoxide (CO) molecules caused the {100} facets of a gold nanoparticle to reconstruct during CO oxidation at room temperature. The CO molecules adsorbed at the on-top sites of gold atoms in the reconstructed surface, and the energetic favorability of this reconstructed structure was confirmed by ab initio calculations and image simulations. This atomic-scale visualizing method can be applied to help elucidate reaction mechanisms in heterogeneous catalysis.

In Situ Industrial Bimetallic Catalyst Characterization using Scanning Transmission Electron Microscopy and X‐ray Absorption Spectroscopy at One Atmosphere and Elevated Temperature

“…This has led to an explosion of interest in in situ TEM, where materials are studied under more realistic environmental conditions 21, 22, 23. Dedicated environmental transmission electron microscope (ETEM) systems allow for atomic resolution imaging at moderate temperature but are limited to pressures of less than ≈50 mbar 24, 25, 26.…”

“…Since different nanoparticle structures may have varying catalytic activity,13 an understanding of the different particle types observed gives additional insight into catalytic performance. This is particularly important in cases where particle morphology is affected by the environment 20, 21, 22. In systems such as these, in situ high spatial resolution EDS is required to observe the true nanostructures and their compositional distribution as shown in Figure 3 f. …”

Design of a new reactor-like high temperature near ambient pressure scanning tunneling microscope for catalysis studies

“…Atoms in surface layer and even nearly surface layers are significantly impacted by the existence of environment. [2][3][4][5][6] The complexity is largely enhanced when the catalyst functions at a high temperature.…”

Catalysis using colloidal-supported gold-based nanoparticles

“…After these important discoveries, many research groups in academia and industry have focused their research upon exploring the catalytic performance of Au catalysts for a wide range of oxidation and hydrogenation reactions [5,6]. New discoveries have been reported since that period, and novel, designed supported gold nanoparticles have shown to be extremely effective catalysts for the oxidation of CO [7][8][9][10][11], the selective oxidation of alcohols and polyols [12,13], the epoxidation of olefins [14,15], the hydrochlorination of ethyne [16], the selective hydrogenation of unsaturated carbonyl and nitro groups [17], and the direct synthesis of hydrogen peroxide from molecular hydrogen and oxygen [18]. Whilst these monometallic Au nanoparticles have been shown to be effective redox catalysts, we have shown over the last decade that using bimetallic catalysts, such as Au-Pd catalysts, a significant improvement in terms of catalytic reactivity and stability for a range of reactions, such as the oxidation of alcohols [19] and hydrogen peroxide synthesis [20][21][22], could be observed.…”