Resolving the Structure of Active Sites on Platinum Catalytic Nanoparticles

Chang, Shery L. Y.; Barnard, Amanda S.; Gontard, Lionel C.; Dunin-Borkowski, Rafal E.

doi:10.1021/nl101642f

Cited by 107 publications

(103 citation statements)

References 24 publications

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“…2b is in reasonable agreement with Huang's report of 22-pm contraction of edge and corner bonds but is in disagreement with Chang's report of 14-30-pm bond length expansion of a similar (110) À (1 Â 1) reconstructed (1 11)/( 1 11) corner. However, Chang also reports density functional theory (DFT) calculations that predict the contraction of a (110) À (1 Â 1) reconstructed (1 11)/( 1 11) corner 10 , in reasonable agreement with our results. We report expansion of a (1 11) surface, as does Chang, but Huang reports only contraction.…”

Section: Discussionsupporting

confidence: 88%

“…Comparable measurements have been made on Pt nanocatalysts on a carbon support by Chang et al 10 using TEM and on faceted Au NPs dispersed on graphene by Huang et al 27 using coherent electron nanodiffraction. The bond length contraction near the corner in Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Transmission electron microscopy (TEM) and scanning TEM (STEM) have been used nearly since their inception for NP characterization but have been limited by the available resolution and precision [7][8][9][10] . Aberration correction has made sub-Angstrom spatial resolution routine in TEM and STEM.…”

mentioning

confidence: 99%

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Picometre-precision analysis of scanning transmission electron microscopy images of platinum nanocatalysts

et al. 2014

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Measuring picometre-scale shifts in the positions of individual atoms in materials provides new insight into the structure of surfaces, defects and interfaces that influence a broad variety of materials' behaviour. Here we demonstrate sub-picometre precision measurements of atom positions in aberration-corrected Z-contrast scanning transmission electron microscopy images based on the non-rigid registration and averaging of an image series. Non-rigid registration achieves five to seven times better precision than previous methods. Non-rigidly registered images of a silica-supported platinum nanocatalyst show pm-scale contraction of atoms at a (1 11)/( 1 11) corner towards the particle centre and expansion of a flat (1 11) facet. Sub-picometre precision and standardless atom counting with o1 atom uncertainty in the same scanning transmission electron microscopy image provide new insight into the threedimensional atomic structure of catalyst nanoparticle surfaces, which contain the active sites controlling catalytic reactions.

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Section: Discussionsupporting

confidence: 88%

Section: Discussionmentioning

confidence: 99%

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Picometre-precision analysis of scanning transmission electron microscopy images of platinum nanocatalysts

et al. 2014

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“…This is similar to the case of large nano- 10 particles that are single crystals in which defects concentrate on the surfaces [28,29].…”

supporting

confidence: 64%

Oxygen reduction on nanostructured platinum surfaces in acidic media: Promoting effect of surface steps and ideal response of Pt(1 1 1)

Gómez–Marín

Feliu

2015

Catalysis Today

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Abstract:In this paper, the role of surface steps on the electrocatalytic activity of Platinum nano-10 structured surfaces for the oxygen reduction reaction (ORR) in acidic medium is evaluated by using stepped surfaces of structure Pt(S)[n(111)x (111)] with large terraces (20 ≤ n ≤ 50). It is realized that the inclusion of an even low amount of surface steps enhances the ORR, and linear activity trends are measured when currents at constant potential are plotted vs. the step density. As a consequence, an ideal ORR curve for a 15 defect-free Pt(111) surface is extrapolated at zero defect density from experimental data and can be compared to that of a quasi perfect Pt(111) electrode. It is clearly shown that surface steps promote the electrode activity toward ORR in acid medium. Results are discussed in light of available theoretical and experimental data.

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“…Heterogeneous catalysis is a particular application in which, the structure, morphology, and chemistry of nanoparticles are dynamic and greatly depend on the gas environment and temperature [1][2][3][4][5][6][7] . Unfortunately, conventional high-resolution TEM of catalysis is extremely challenging since both ambient pressure and elevated temperature can adversely affect imaging conditions.…”

mentioning

confidence: 99%

A (S)TEM Gas Cell Holder with Localized Laser Heating forIn SituExperiments

Mehraeen

McKeown

Deshmukh³

et al. 2013

Microsc Microanal

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The advent of aberration correction for transmission electron microscopy has transformed atomic resolution imaging into a nearly routine technique for structural analysis. Now an emerging frontier in electron microscopy is the development of in situ capabilities to observe reactions at atomic resolution in real-time and within realistic environments. Here we present a new in situ gas holder that was designed to bypass several limitations that have plagued previous in situ gas holders. The new holder is compatible with any type of sample, and its capabilities include localized heating and precise control of the gas pressure and composition while simultaneously allowing atomic resolution imaging at ambient pressure. The results show that 0.25 nm lattice fringes are directly visible for nanoparticles imaged at ambient pressure with gas path lengths up to 20 µm. Additionally, we quantitatively demonstrate that while the attainable contrast and resolution decrease with increasing pressure and gas path length, resolutions better than 0.2 nm should be accessible at ambient pressure with gas path lengths less than the 15 µm utilized for these experiments. 3The ability to study gas-solid interactions with atomic resolution and ambient pressures in the transmission electron microscope (TEM) promises new insights into the growth, properties, and functionality of nanomaterials. Heterogeneous catalysis is a particular application in which, the structure, morphology, and chemistry of nanoparticles are dynamic and greatly depend on the gas environment and temperature [1][2][3][4][5][6][7] . Unfortunately, conventional high-resolution TEM of catalysis is extremely challenging since both ambient pressure and elevated temperature can adversely affect imaging conditions. This is further complicated by the fact that normal TEM imaging is performed under a high vacuum (1.5x10 -7 Torr) to prevent unwanted scattering from gases. Therefore, to enable in situ experiments within the column of an electron microscope, a localized gas environmental chamber with controllable gas pressure, composition, and temperature is crucial. Such conditions can be obtained using an environmental cell built around the specimen.The original designs for environmental cells have been around for over 70 years 8 and are produced by either incorporating differentially pumped apertures that separate the specimen from the high vacuum of the TEM column 1, 9-16 or windowed-cell designs that confine the gas within the specimen holder using electron-transparent membranes 4,10,[17][18][19][20][21][22] . Atomic-resolution images in gaseous environments have been obtained with both techniques at pressures up to ~10 Torr 1,5,15,22,23 , but the technological relevance of these measurements may not be compatible with the more realistic operating conditions of catalyst nanomaterials at higher pressures. Environmental transmission electron microscopes (ETEM) that incorporate differentially pumped apertures are generally limited to pressures of 15-20 Torr but they per...

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Resolving the Structure of Active Sites on Platinum Catalytic Nanoparticles

Cited by 107 publications

References 24 publications

Picometre-precision analysis of scanning transmission electron microscopy images of platinum nanocatalysts

Picometre-precision analysis of scanning transmission electron microscopy images of platinum nanocatalysts

Oxygen reduction on nanostructured platinum surfaces in acidic media: Promoting effect of surface steps and ideal response of Pt(1 1 1)

A (S)TEM Gas Cell Holder with Localized Laser Heating forIn SituExperiments

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