Transformations of Supported Gold Nanoparticles Observed by In Situ Electron Microscopy

In situ manipulation of the active Au-TiO 2 interface with atomic precision during CO oxidation

“…Recent in situ experiments indicate that refacetting of NPs and surface reconstructions of the substrates can occur in reactive environments (17)(18)(19)(20)(21)(22)(23)(24)(25), but little is known about the dependence of the intrinsic interface on the surrounding environment (26). Although structural changes of the interface induced by the electron beam (e beam) have been reported (26)(27)(28), it is unclear whether the intrinsic interface changes in reactive environments, and whether the catalytic interface can be manipulated with atomic precision during reactions (29)(30)(31)(32).…”

“…The experiments were performed in a spherical aberration (Cs)-corrected ETEM (FEI Titan 80-300 ST), equipped with a heating holder (DENSsolutions Wildfire S3). To avoid the e-beam induced reconstruction of the interface as reported in previous in situ studies (26)(27)(28), we chose to use low e-beam dose (6.45×10 -1 to 8.73×10 -1 A/cm 2 ) and a Gatan OneView CMOS camera in this work to obtain the atomic in situ images of the intrinsic interface structure based on a previous work (26). We loaded Au NPs [diameter: 4~8 nm] on TiO2 nanosheets with dominant (001) surfaces [length: ~30 nm; thickness: ~5 nm] (33-36) using impregnation and annealing approaches.…”

Reversible transformation between terrace and step sites of Pt nanoparticles on titanium under CO and O2 environments

“…However, it could be spontaneously dissolved on Pt {111} and {100} step sites, with the significantly lower adsorption energies of 2.00 and 2.37 eV, respectively. As a result, once {111} step sites came into being on {111} terrace sites due to the thermal agitation [56][57][58], O atoms will be strongly adsorbed on {111} step sites and stabilize these sites. This result could well explain our in situ experimental results.…”

Electron beam effects in high-resolution transmission electron microscopy investigations of catalytic nanoparticles

“…In an attempt to isolate the electron beam effects from effects of the environment, we carry out a systematic study varying the beam intensity (dose rate) at different temperatures, both in high vacuum and in the presence of relevant reactant gases. The current model system consists of gold nanoparticles supported on cerium dioxide [3,4]. The aforementioned studies elucidate how the nanoparticles undergo changes with observation time and reactant gases present, and surface events as function of dose rate, respectively.…”