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Title: Oxygen Deficiency and Reactivity of Spinel NiCo 2O 4 (001) Surfaces

Abstract

We carried out density functional theory (DFT) calculations with on-site Hubbard U corrections to investigate the structure, defects, and reactivity of (001) surfaces of spinel NiCo 2O 4 (NCO), a promising catalyst for CO and methane oxidation. By examining surfaces with different Co/Ni compositions, we find that the formation of surface oxygen vacancies (VOs) on NCO(001) is strongly affected by the neighboring cation in the third layer, the computed formation energy being largest (~1.2 eV) for O vacancies coordinated to third layer Co and smallest (~0.5 eV) for VOs coordinated to a Ni neighboring another Ni ion. As a result, VO formation is generally much easier on NCO (001) than on Co 3O 4 (001) surfaces, suggesting that NCO may be a better catalyst than Co 3O 4 for oxidation reactions based on the Mars–Van Krevelen mechanism. Surface oxygen vacancies on reduced NCO surfaces can be healed through dissociative water adsorption at room temperature. In contrast, adsorption of molecular oxygen at VOs is energetically unfavorable under ambient conditions, suggesting that O 2 adsorption may represent the thermodynamic limiting step for oxidation reactions on NCO(001) surfaces.

Authors:
 [1];  [2]; ORCiD logo [1]
  1. Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
  2. Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States; Science Division, Yale-NUS College, Singapore 138609, Singapore
Publication Date:
Research Org.:
Lawrence Berkeley National Laboratory-National Energy Research Scientific Computing Center
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Chemical Sciences, Geosciences & Biosciences Division
OSTI Identifier:
1480449
DOE Contract Number:  
SC0007347; AC02-05CH11231
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: 121; Journal Issue: 7; Journal ID: ISSN 1932-7447
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English

Citation Formats

Shi, Xiao, Bernasek, Steven L., and Selloni, Annabella. Oxygen Deficiency and Reactivity of Spinel NiCo2O4 (001) Surfaces. United States: N. p., 2017. Web. doi:10.1021/acs.jpcc.6b12005.
Shi, Xiao, Bernasek, Steven L., & Selloni, Annabella. Oxygen Deficiency and Reactivity of Spinel NiCo2O4 (001) Surfaces. United States. https://doi.org/10.1021/acs.jpcc.6b12005
Shi, Xiao, Bernasek, Steven L., and Selloni, Annabella. Thu . "Oxygen Deficiency and Reactivity of Spinel NiCo2O4 (001) Surfaces". United States. https://doi.org/10.1021/acs.jpcc.6b12005.
@article{osti_1480449,
title = {Oxygen Deficiency and Reactivity of Spinel NiCo2O4 (001) Surfaces},
author = {Shi, Xiao and Bernasek, Steven L. and Selloni, Annabella},
abstractNote = {We carried out density functional theory (DFT) calculations with on-site Hubbard U corrections to investigate the structure, defects, and reactivity of (001) surfaces of spinel NiCo2O4 (NCO), a promising catalyst for CO and methane oxidation. By examining surfaces with different Co/Ni compositions, we find that the formation of surface oxygen vacancies (VOs) on NCO(001) is strongly affected by the neighboring cation in the third layer, the computed formation energy being largest (~1.2 eV) for O vacancies coordinated to third layer Co and smallest (~0.5 eV) for VOs coordinated to a Ni neighboring another Ni ion. As a result, VO formation is generally much easier on NCO (001) than on Co3O4 (001) surfaces, suggesting that NCO may be a better catalyst than Co3O4 for oxidation reactions based on the Mars–Van Krevelen mechanism. Surface oxygen vacancies on reduced NCO surfaces can be healed through dissociative water adsorption at room temperature. In contrast, adsorption of molecular oxygen at VOs is energetically unfavorable under ambient conditions, suggesting that O2 adsorption may represent the thermodynamic limiting step for oxidation reactions on NCO(001) surfaces.},
doi = {10.1021/acs.jpcc.6b12005},
url = {https://www.osti.gov/biblio/1480449}, journal = {Journal of Physical Chemistry. C},
issn = {1932-7447},
number = 7,
volume = 121,
place = {United States},
year = {2017},
month = {2}
}