NH3 on anatase TiO2(101): Diffusion mechanisms and the effect of intermolecular repulsion

Kræn Christoffer Adamsen; Esben Leonhard Kolsbjerg; Stig Koust; Lutz Lammich; Bjørk Hammer; Stefan Wendt; Jeppe Vang Lauritsen

doi:10.1103/PhysRevMaterials.4.121601

NH₃on anatase TiO₂(101): Diffusion mechanisms and the effect of intermolecular repulsion

Kræn Christoffer Adamsen, Esben Leonhard Kolsbjerg, Stig Koust, Lutz Lammich, Bjørk Hammer, Stefan Wendt, Jeppe Vang Lauritsen^*

^*Corresponding author af dette arbejde

Publikation: Bidrag til tidsskrift/Konferencebidrag i tidsskrift /Bidrag til avis › Tidsskriftartikel › Forskning › peer review

Abstract

We utilized scanning tunneling microscopy (STM) experiments and density functional theory (DFT) calculations to study the diffusion of ammonia (NH3) on anatase TiO2(101). From time-lapsed STM imaging, we observed monomeric and dimeric diffusion channels, and a general tendency to higher diffusion rates with increasing NH3 coverage. In surface regions where several NH3 molecules are adsorbed within a few sites, we further observed the diffusion of NH3 molecules occurring in cascades, where the diffusion of one adsorbate triggers that of others. This eventually leads to apparent diffusion barriers that are lower than expected within a single-jump model. From the DFT calculations, we obtained mechanistic insights into the two observed NH3 diffusion channels. Within the dimeric NH3 diffusion channel, one NH3 swings around another adsorbed NH3 and experiences a reduced diffusion barrier, owing to the intermolecular bonding during the event.

Originalsprog	Engelsk
Artikelnummer	121601(R)
Tidsskrift	Physical Review Materials
Vol/bind	4
Nummer	12
ISSN	2476-0455
DOI	https://doi.org/10.1103/PhysRevMaterials.4.121601
Status	Udgivet - dec. 2020

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10.1103/PhysRevMaterials.4.121601

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Citationsformater

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title = "NH3 on anatase TiO2(101): Diffusion mechanisms and the effect of intermolecular repulsion",

abstract = "We utilized scanning tunneling microscopy (STM) experiments and density functional theory (DFT) calculations to study the diffusion of ammonia (NH3) on anatase TiO2(101). From time-lapsed STM imaging, we observed monomeric and dimeric diffusion channels, and a general tendency to higher diffusion rates with increasing NH3 coverage. In surface regions where several NH3 molecules are adsorbed within a few sites, we further observed the diffusion of NH3 molecules occurring in cascades, where the diffusion of one adsorbate triggers that of others. This eventually leads to apparent diffusion barriers that are lower than expected within a single-jump model. From the DFT calculations, we obtained mechanistic insights into the two observed NH3 diffusion channels. Within the dimeric NH3 diffusion channel, one NH3 swings around another adsorbed NH3 and experiences a reduced diffusion barrier, owing to the intermolecular bonding during the event.",

author = "Adamsen, {Kr{\ae}n Christoffer} and Kolsbjerg, {Esben Leonhard} and Stig Koust and Lutz Lammich and Bj{\o}rk Hammer and Stefan Wendt and Lauritsen, {Jeppe Vang}",

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T2 - Diffusion mechanisms and the effect of intermolecular repulsion

AU - Adamsen, Kræn Christoffer

AU - Kolsbjerg, Esben Leonhard

AU - Koust, Stig

AU - Lammich, Lutz

AU - Hammer, Bjørk

AU - Wendt, Stefan

AU - Lauritsen, Jeppe Vang

PY - 2020/12

Y1 - 2020/12

N2 - We utilized scanning tunneling microscopy (STM) experiments and density functional theory (DFT) calculations to study the diffusion of ammonia (NH3) on anatase TiO2(101). From time-lapsed STM imaging, we observed monomeric and dimeric diffusion channels, and a general tendency to higher diffusion rates with increasing NH3 coverage. In surface regions where several NH3 molecules are adsorbed within a few sites, we further observed the diffusion of NH3 molecules occurring in cascades, where the diffusion of one adsorbate triggers that of others. This eventually leads to apparent diffusion barriers that are lower than expected within a single-jump model. From the DFT calculations, we obtained mechanistic insights into the two observed NH3 diffusion channels. Within the dimeric NH3 diffusion channel, one NH3 swings around another adsorbed NH3 and experiences a reduced diffusion barrier, owing to the intermolecular bonding during the event.

AB - We utilized scanning tunneling microscopy (STM) experiments and density functional theory (DFT) calculations to study the diffusion of ammonia (NH3) on anatase TiO2(101). From time-lapsed STM imaging, we observed monomeric and dimeric diffusion channels, and a general tendency to higher diffusion rates with increasing NH3 coverage. In surface regions where several NH3 molecules are adsorbed within a few sites, we further observed the diffusion of NH3 molecules occurring in cascades, where the diffusion of one adsorbate triggers that of others. This eventually leads to apparent diffusion barriers that are lower than expected within a single-jump model. From the DFT calculations, we obtained mechanistic insights into the two observed NH3 diffusion channels. Within the dimeric NH3 diffusion channel, one NH3 swings around another adsorbed NH3 and experiences a reduced diffusion barrier, owing to the intermolecular bonding during the event.

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