From Single Atoms to Nanoparticles: Autocatalysis and Metal Aggregation in Atomic Layer Deposition of Pt on TiO2 Nanopowder

Fabio Grillo* (Corresponding Author), Hao Van Bui, Damiano La Zara, Antonius A.I. Aarnink, Alexey Y. Kovalgin, Patricia Kooyman, Michiel T. Kreutzer, Jan Rudolf van Ommen

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

20 Citations (Scopus)

Abstract

A fundamental understanding of the interplay between ligand-removal kinetics and metal aggregation during the formation of platinum nanoparticles (NPs) in atomic layer deposition of Pt on TiO2 nanopowder using trimethyl(methylcyclo-pentadienyl)platinum(IV) as the precursor and O2 as the coreactant is presented. The growth follows a pathway from single atoms to NPs as a function of the oxygen exposure (PO2 × time). The growth kinetics is modeled by accounting for the autocatalytic combustion of the precursor ligands via a variant of the Finke–Watzky two-step model. Even at relatively high oxygen exposures (<120 mbar s) little to no Pt is deposited after the first cycle and most of the Pt is atomically dispersed. Increasing the oxygen exposure above 120 mbar s results in a rapid increase in the Pt loading, which saturates at exposures >> 120 mbar s. The deposition of more Pt leads to the formation of NPs that can be as large as 6 nm. Crucially, high PO2 (≥5 mbar) hinders metal aggregation, thus leading to narrow particle size distributions. The results show that ALD of Pt NPs is reproducible across small and large surface areas if the precursor ligands are removed at high PO2.

Original languageEnglish
Article number1800765
JournalSmall
Volume14
Issue number23
DOIs
Publication statusPublished - 7 Jun 2018

Keywords

  • UT-Hybrid-D
  • Atomic layer deposition
  • Kinetics
  • Nanoparticles
  • Size distribution
  • Aggregation

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