Title: Interfacial Effects on the Band Edges of Functionalized Si Surfaces in Liquid Water

Abstract

By combining ab initio molecular dynamics simulations and many-body perturbation theory calculations of electronic energy levels, we determined the band edge positions of functionalized Si(111) surfaces in the presence of liquid water, with respect to vacuum and to water redox potentials. We considered surface terminations commonly used for Si photoelectrodes in water splitting experiments. We found that, when exposed to water, the semiconductor band edges were shifted by approximately 0.5 eV in the case of hydrophobic surfaces, irrespective of the termination. The effect of the liquid on band edge positions of hydrophilic surfaces was much more significant and determined by a complex combination of structural and electronic effects. These include structural rearrangements of the semiconductor surfaces in the presence of water, changes in the orientation of interfacial water molecules with respect to the bulk liquid, and charge transfer at the interfaces, between the solid and the liquid. Our results showed that the use of many-body perturbation theory is key to obtain results in agreement with experiments; they also showed that the use of simple computational schemes that neglect the detailed microscopic structure of the solid–liquid interface may lead to substantial errors in predicting the alignment between the solid band edgesmore » and water redox potentials.« less

Authors:

Pham, Tuan Anh ^[1]; Lee, Donghwa ^[2]; Schwegler, Eric ^[2]; Galli, Giulia ^[3]

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+ Show Author Affiliations

1. Department of Chemistry, University of California, Davis, California 95616, United States, Lawrence Livermore National Laboratory, Livermore, California 94551, United States
2. Lawrence Livermore National Laboratory, Livermore, California 94551, United States
3. The Institute for Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States

Publication Date:

Wed Nov 26 00:00:00 EST 2014

Research Org.:

Univ. of California, Davis, CA (United States); Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Univ. of Chicago, IL (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES); National Science Foundation (NSF)

OSTI Identifier:

1165322

Alternate Identifier(s):

OSTI ID: 1392319

Grant/Contract Number:  

SC0008938; AC52-07NA27344; CHE-0802907

Resource Type:

Journal Article: Published Article

Journal Name:

Journal of the American Chemical Society

Additional Journal Information:

Journal Name: Journal of the American Chemical Society Journal Volume: 136 Journal Issue: 49; Journal ID: ISSN 0002-7863

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY