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Title: CO 2 Adsorption on Anatase TiO 2 (101) Surfaces in the Presence of Subnanometer Ag/Pt Clusters: Implications for CO 2 Photoreduction

We show how CO2 adsorption on perfect and reduced anatase TiO2 (101) surfaces can be substantially modified by the presence of surface Ag and Pt octamer clusters, using density functional theory calculations. Furthermore, we found that adsorption was affected even at sites where the adsorbate was not in direct contact with the octamer, which we attributed to charge donation to CO2 from the Ag/Pt-modified surface, as well as an electrostatic competition between attractive (Ti–O) and repulsive (Ti–C) interactions. Additionally, TiO2-supported Pt octamers offer key advantages that could be leveraged for CO2 photoreduction, including providing additional stable adsorption sites for bent CO2 species and facilitating charge transfer to aid in CO2– anion formation. Electronic structure analysis suggests these factors arise primarily from the hybridization of the bonding molecular orbitals of CO2 with d orbitals of the Pt atoms. Our results show that, for adsorption on TiO2-supported Pt octamers, the O–C–O bending and C–O asymmetric stretching frequencies can be used as reliable indicators of the presence of the CO2– anion intermediate as well as to distinguish unique adsorption geometries or sites. Finally, we suggest a possible pathway for subsequent CO2 dissociation to CO at the surface of a reduced anatase TiO2 (101)-supportedmore » Pt octamer, which has a computed energy barrier of 1.01 eV.« less
Authors:
 [1] ;  [2] ;  [1] ;  [1]
  1. Univ. of South Florida, Tampa, FL (United States). Dept. of Chemical and Biomedical Engineering
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Quantum Simulations Group
Publication Date:
OSTI Identifier:
1325872
Report Number(s):
LLNL-JRNL--659615
Journal ID: ISSN 1932-7447
Grant/Contract Number:
AC52-07NA27344
Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: 118; Journal Issue: 45; Journal ID: ISSN 1932-7447
Publisher:
American Chemical Society
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
30 DIRECT ENERGY CONVERSION; 36 MATERIALS SCIENCE; 77 NANOSCIENCE AND NANOTECHNOLOGY; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY