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From Single Atoms to Nanoparticles: Autocatalysis and Metal Aggregation in Atomic Layer Deposition of Pt on TiO 2 Nanopowder
Author(s) -
Grillo Fabio,
Bui Hao,
Zara Damiano,
Aarnink Antonius A. I.,
Kovalgin Alexey Y.,
Kooyman Patricia,
Kreutzer Michiel T.,
Ommen Jan Rudolf
Publication year - 2018
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.201800765
Subject(s) - platinum , atomic layer deposition , autocatalysis , kinetics , nanoparticle , deposition (geology) , metal , oxygen , particle size , chemical engineering , materials science , platinum nanoparticles , layer (electronics) , particle (ecology) , nanotechnology , chemistry , catalysis , metallurgy , organic chemistry , paleontology , physics , oceanography , quantum mechanics , sediment , geology , engineering , biology
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 TiO 2 nanopowder using trimethyl(methylcyclo‐pentadienyl)platinum(IV) as the precursor and O 2 as the coreactant is presented. The growth follows a pathway from single atoms to NPs as a function of the oxygen exposure ( P O2 × 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 P O2 (≥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 P O2 .