Reactivity of Structural Oxygens in Platinum Group Metal-Free Co-Doped ATiO<sub>3</sub> (A = Ca, Sr, and Ba) Perovskite Catalysts for CO Oxidation

Platinum group metal-free catalysts can be designed by maximizing the reactivity of structural oxygen in metal oxide catalysts. This study indicates that the symmetry of the perovskite oxide affects the CO oxidation activity and the release behavior of oxygen in the perovskite lattice. Specifically, cubic-type SrTi<sub>0.8</sub>Co<sub>0.2</sub>O<sub>3</sub> and hexagonal-type BaTi<sub>0.8</sub>Co<sub>0.2</sub>O<sub>3</sub> showed much higher CO oxidation activities than orthorhombic-type CaTi<sub>0.8</sub>Co<sub>0.2</sub>O<sub>3</sub>. The oxygen-release properties evaluated under H<sub>2</sub> flow show that SrTi<sub>0.8</sub>Co<sub>0.2</sub>O<sub>3</sub> and BaTi<sub>0.8</sub>Co<sub>0.2</sub>O<sub>3</sub> exhibit better performance and structural stability than CaTi<sub>0.8</sub>Co<sub>0.2</sub>O<sub>3</sub>. Density functional theory calculations of the energy required for the oxygen desorption reveal that the Δ<i>R</i> value, which denotes the difference in the Co-O bond lengths between the oxidized and reduced states of Co-doped ATiO<sub>3</sub>, is a valid indicator of the oxygen reactivity and structural stability. The Δ<i>R</i> value primarily depends on the symmetry of the crystal structure and the magnetic moment of the Co ion. The structural oxygen in SrTi<sub>0.8</sub>Co<sub>0.2</sub>O<sub>3</sub> or BaTi<sub>0.8</sub>Co<sub>0.2</sub>O<sub>3</sub>, which have smaller Δ<i>R</i> values than that of CaTi<sub>0.8</sub>Co<sub>0.2</sub>O<sub>3</sub>, can be desorbed at lower energy. This study clearly demonstrates that the reactivity of structural oxygens in a metal oxide catalyst can be controlled by adjusting the symmetry of the perovskite unit.

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Journal
Inorganic Chemistry
Published
2025-10-04
DOI
https://doi.org/10.1021/acs.inorgchem.5c02455
Primary Topic
Catalytic Processes in Materials Science
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article
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article

Reactivity of Structural Oxygens in Platinum Group Metal-Free Co-Doped ATiO3 (A = Ca, Sr, and Ba) Perovskite Catalysts for CO Oxidation

R. Sugimoto, Takashi Yumura, Saburo Hosokawa
Inorganic Chemistry
Catalytic Processes in Materials Science
article

Reactivity of Structural Oxygens in Platinum Group Metal-Free Co-Doped ATiO3 (A = Ca, Sr, and Ba) Perovskite Catalysts for CO Oxidation

R. Sugimoto, Takashi Yumura, Saburo Hosokawa
article en

Abstract

Platinum group metal-free catalysts can be designed by maximizing the reactivity of structural oxygen in metal oxide catalysts. This study indicates that the symmetry of the perovskite oxide affects the CO oxidation activity and the release behavior of oxygen in the perovskite lattice. Specifically, cubic-type SrTi<sub>0.8</sub>Co<sub>0.2</sub>O<sub>3</sub> and hexagonal-type BaTi<sub>0.8</sub>Co<sub>0.2</sub>O<sub>3</sub> showed much higher CO oxidation activities than orthorhombic-type CaTi<sub>0.8</sub>Co<sub>0.2</sub>O<sub>3</sub>. The oxygen-release properties evaluated under H<sub>2</sub> flow show that SrTi<sub>0.8</sub>Co<sub>0.2</sub>O<sub>3</sub> and BaTi<sub>0.8</sub>Co<sub>0.2</sub>O<sub>3</sub> exhibit better performance and structural stability than CaTi<sub>0.8</sub>Co<sub>0.2</sub>O<sub>3</sub>. Density functional theory calculations of the energy required for the oxygen desorption reveal that the Δ<i>R</i> value, which denotes the difference in the Co-O bond lengths between the oxidized and reduced states of Co-doped ATiO<sub>3</sub>, is a valid indicator of the oxygen reactivity and structural stability. The Δ<i>R</i> value primarily depends on the symmetry of the crystal structure and the magnetic moment of the Co ion. The structural oxygen in SrTi<sub>0.8</sub>Co<sub>0.2</sub>O<sub>3</sub> or BaTi<sub>0.8</sub>Co<sub>0.2</sub>O<sub>3</sub>, which have smaller Δ<i>R</i> values than that of CaTi<sub>0.8</sub>Co<sub>0.2</sub>O<sub>3</sub>, can be desorbed at lower energy. This study clearly demonstrates that the reactivity of structural oxygens in a metal oxide catalyst can be controlled by adjusting the symmetry of the perovskite unit.

Inorganic ChemistryVol. 64(41)
Kyoto Institute of Technology (JP)
Openalex Percentile: Top 79%
Catalytic Processes in Materials Science
DOISourceOpenAlex
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Reactivity of Structural Oxygens in Platinum Group Metal-Free Co-Doped ATiO<sub>3</sub> (A = Ca, Sr, and Ba) Perovskite Catalysts for CO Oxidation — R. Sugimoto, Takashi Yumura, et al. · Inorganic Chemistry (2025) | TGRS Research Map | TGRS