Visualization of oscillatory behaviour of Pt nanoparticles catalysing CO oxidation
Evidence and attribution¶
Authority of statements
Prose sections below (Summary, Methods, Findings, etc.) are curated summaries of the publication identified by doi, title, and pdf_path in the front matter above. They are not new primary claims by this wiki.
For definitive numerical values, reaction schemes, and interpretations, use the peer-reviewed article (and optional records under normalized/papers/ when present), not this page alone.
Summary¶
Operando electron microscopy in a MEMS nanoreactor at near 1 bar and relevant temperatures ties time-resolved CO oxidation turnover oscillations on Pt nanoparticles to periodic particle refacetting. Mass spectrometry and calorimetry alongside HR-TEM show that conversion swings co-vary with facet rearrangements: higher conversion associates with more close-packed terminations and lower conversion with more stepped / high-index character (as summarized in the article). DFT plus transport-aware modeling argues that refacetting is needed to explain the oscillations beyond adsorbate / kinetic bistability alone.
Methods¶
Local sources: the PDF at papers/Others/Vendelbo_nmat_2014_Pt_oscillation.pdf is present in this workspace and is the primary reading copy. No normalized/extracts/2014vendelbo-nat-visualization-oscillatory_*.txt file is in this clone; the protocol below is taken from the PDF (DOI 10.1038/nmat4033, Nat. Mater. 13, 889–893 (2014)).
The study uses a MEMS nanoreactor with a unidirectional gas channel, a heated reaction zone at \(\sim\)1 bar and temperatures representative of automotive exhaust catalysis, and electron-transparent windows for high-resolution TEM of Pt nanoparticles supported on the window. Steady-state gas-flow simulations of CO partial pressure inside the reactor (Fig. 1d–e, Supplementary material) use inlet compositions stated as 1.0 bar total of CO/O\(_2\)/He at 4.2% / 21.0% / 74.8% with geometry from Supplementary Tables 1–2. Time-resolved measurements couple HR-TEM of particle shape/facets, mass spectrometry of the effluent, and reaction calorimetry. DFT supplies site-dependent CO adsorption and oxidation inputs, combined with mass-transport calculations, to test whether kinetic bistability plus transport suffices or facet refacetting must be included.
Static QM / DFT (supporting calculations). DFT supplies site-dependent CO adsorption/oxidation inputs combined with mass-transport modeling to test whether kinetic bistability plus transport alone can explain oscillations versus requiring facet refacetting. Full functional, dispersion, basis/plane-wave settings, k-mesh choices, slab models, and energy tables are N/A on this wiki page—see papers/Others/Vendelbo_nmat_2014_Pt_oscillation.pdf and Supplementary Information.
MD application. N/A: the paper is not an atomistic MD methods study; “dynamics” here are experimental nanoparticle refacetting plus continuum/transport and DFT-informed modeling.
Findings¶
The work demonstrates time-resolved, operando visualization of CO oxidation turnover oscillations on Pt nanoparticles while correlating gas-phase conversion with particle-level structural dynamics. The authors argue that periodic refacetting—cycling between more close-packed facet terminations at higher conversion and more open/stepped terminations at lower conversion—provides a structural periodicity aligned with the rate oscillations, supporting a picture where nanoparticle morphology dynamics can couple to catalytic bistability/oscillations in ways that differ from classical extended single-crystal surface oscillation scenarios.
Quantitative turnover/facet correlations, DFT/transport sensitivity tests, and discussion caveats are in papers/Others/Vendelbo_nmat_2014_Pt_oscillation.pdf and SI.
Limitations¶
- Electron-beam effects and near-atmospheric TEM constraints still bound quantitative turnover interpretation; DFT covers idealized facets vs real particle shapes.
Relevance to group¶
Demonstrates in situ structure-activity coupling for oxidation catalysis, complementary context to ReaxFF surface simulation papers that also target dynamic oxide / metal interfaces.
Citations and evidence anchors¶
- DOI: https://doi.org/10.1038/nmat4033 - Nat. Mater. 13, 889-893 (2014).