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Title: Formic Acid Adsorption on Anatase TiO 2(001)-(1 × 4) Thin Films Studied by NC-AFM and STM

Abstract

Atomic resolution scanning tunneling microscopy (STM), non-contact atomic force microscopy (NC-AFM), X-ray photoemission spectroscopy (XPS), low-energy electron diffraction (LEED) and formic acid adsorption experiments were used to characterize the (001) surface of anatase TiO 2. A combination of NC-AFM and STM imaging was used to distinguish features due to geometrical and electronic effects. The contrast in images of the bare (1 × 4) surface and the formate-covered surface is dominated by the surface topography in both NC-AFM and STM, although electronic effects in the troughs contribute features to the STM images that are absent from NC-AFM images. High resolution imaging by STM and NC-AFM revealed that the highest point of the ridge of the (1 × 4) structure consists of a single row of atoms. Formate adsorbs at under-coordinated Ti sites in the added rows with a minimum separation of 2a 0, and never adsorbs in the trenches even though the trenches also likely expose under-coordinated Ti atoms. The sticking probability of formate on the anatase TiO 2(001)-(1 × 4) surface is near unity initially, and falls dramatically once the saturation coverage of 1/8 ML is reached. We show that of the current models for the (1 × 4) reconstruction,more » an added row plus surface oxygen vacancy model and the recently proposed ad-molecule model are in best agreement with all of the data.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1423427
Report Number(s):
PNNL-SA-36055
Journal ID: ISSN 1520-6106; KP1704020
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry. B, Condensed Matter, Materials, Surfaces, Interfaces and Biophysical Chemistry
Additional Journal Information:
Journal Volume: 106; Journal Issue: 33; Journal ID: ISSN 1520-6106
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
STM; NC-AFM; XPS; LEED; anatase TiO2; oxygen

Citation Formats

Tanner, Robert E., Sasahara, Akira, Liang, Yong, Altman, Eric I., and Onishi, Hiroshi. Formic Acid Adsorption on Anatase TiO2(001)-(1 × 4) Thin Films Studied by NC-AFM and STM†. United States: N. p., 2002. Web. doi:10.1021/jp020617y.
Tanner, Robert E., Sasahara, Akira, Liang, Yong, Altman, Eric I., & Onishi, Hiroshi. Formic Acid Adsorption on Anatase TiO2(001)-(1 × 4) Thin Films Studied by NC-AFM and STM†. United States. doi:10.1021/jp020617y.
Tanner, Robert E., Sasahara, Akira, Liang, Yong, Altman, Eric I., and Onishi, Hiroshi. Thu . "Formic Acid Adsorption on Anatase TiO2(001)-(1 × 4) Thin Films Studied by NC-AFM and STM†". United States. doi:10.1021/jp020617y.
@article{osti_1423427,
title = {Formic Acid Adsorption on Anatase TiO2(001)-(1 × 4) Thin Films Studied by NC-AFM and STM†},
author = {Tanner, Robert E. and Sasahara, Akira and Liang, Yong and Altman, Eric I. and Onishi, Hiroshi},
abstractNote = {Atomic resolution scanning tunneling microscopy (STM), non-contact atomic force microscopy (NC-AFM), X-ray photoemission spectroscopy (XPS), low-energy electron diffraction (LEED) and formic acid adsorption experiments were used to characterize the (001) surface of anatase TiO2. A combination of NC-AFM and STM imaging was used to distinguish features due to geometrical and electronic effects. The contrast in images of the bare (1 × 4) surface and the formate-covered surface is dominated by the surface topography in both NC-AFM and STM, although electronic effects in the troughs contribute features to the STM images that are absent from NC-AFM images. High resolution imaging by STM and NC-AFM revealed that the highest point of the ridge of the (1 × 4) structure consists of a single row of atoms. Formate adsorbs at under-coordinated Ti sites in the added rows with a minimum separation of 2a0, and never adsorbs in the trenches even though the trenches also likely expose under-coordinated Ti atoms. The sticking probability of formate on the anatase TiO2(001)-(1 × 4) surface is near unity initially, and falls dramatically once the saturation coverage of 1/8 ML is reached. We show that of the current models for the (1 × 4) reconstruction, an added row plus surface oxygen vacancy model and the recently proposed ad-molecule model are in best agreement with all of the data.},
doi = {10.1021/jp020617y},
journal = {Journal of Physical Chemistry. B, Condensed Matter, Materials, Surfaces, Interfaces and Biophysical Chemistry},
issn = {1520-6106},
number = 33,
volume = 106,
place = {United States},
year = {2002},
month = {8}
}