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Catalytic activities of noble metal atoms on WO3 (001): nitric oxide adsorption.

Ren X, Zhang S, Li C, Li S, Jia Y, Cho JH - Nanoscale Res Lett (2015)

Bottom Line: This relatively stronger bonding of NO to the W atom is found to be associated with the larger charge transfer of 0.43 e (Cu) and 0.33 e (Ag) from the surface to adsorbed NO.On such an Au-WO3(001) complex, the NO molecule is found to form a bond to the Au atom with E ads = -1.32 eV.Because of a large electronegativity of Au atom, the adsorbed NO molecule captures the less electrons (0.04 e) from the surface compared to the Cu and Ag catalysts.

View Article: PubMed Central - PubMed

Affiliation: International Laboratory for Quantum Functional Materials of Henan, and School of Physics and Engineering, Zhengzhou University, Zhengzhou, 450001 China ; School of Mechanical and Electrical Engineering, Henan Institute of Science and Technology, Xinxiang, 453003 China.

ABSTRACT
Using first-principles density functional theory calculations within the generalized gradient approximation, we investigate the adsorption of NO molecule on a clean WO3(001) surface as well as on the noble metal atom (Cu, Ag, and Au)-deposited WO3(001) surfaces. We find that on a clean WO3 (001) surface, the NO molecule binds to the W atom with an adsorption energy (E ads) of -0.48 eV. On the Cu- and Ag-deposited WO3(001) surface where such noble metal atoms prefer to adsorb on the hollow site, the NO molecule also binds to the W atom with E ads = -1.69 and -1.41 eV, respectively. This relatively stronger bonding of NO to the W atom is found to be associated with the larger charge transfer of 0.43 e (Cu) and 0.33 e (Ag) from the surface to adsorbed NO. However, unlike the cases of Cu-WO3(001) and Ag-WO3(001), Au atoms prefer to adsorb on the top of W atom. On such an Au-WO3(001) complex, the NO molecule is found to form a bond to the Au atom with E ads = -1.32 eV. Because of a large electronegativity of Au atom, the adsorbed NO molecule captures the less electrons (0.04 e) from the surface compared to the Cu and Ag catalysts. Our findings not only provide useful information about the NO adsorption on a clean WO3(001) surface as well as on the noble metal atoms deposited WO3(001) surfaces but also shed light on a higher sensitive WO3 sensor for NO detection employing noble metal catalysts.

No MeSH data available.


Optimized atomic structure. (a) Top view and (b) side view of the clean WO3 (001) surface. The large and small circles represent W and O atoms, respectively. The most stable structures for the Cu, Ag, and Au atoms deposited on WO3 (001) surface are displayed in (c), (d), and (e), respectively. The most stable structures for NO adsorption on a clean WO3 (001) surface and the Cu-, Ag-, and Au-deposited WO3 (001) surfaces are displayed in (f), (g), (h), and (i), respectively. In (f), (g), (h), and (i), the circle for N atom is larger than that for the O atom.
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Fig1: Optimized atomic structure. (a) Top view and (b) side view of the clean WO3 (001) surface. The large and small circles represent W and O atoms, respectively. The most stable structures for the Cu, Ag, and Au atoms deposited on WO3 (001) surface are displayed in (c), (d), and (e), respectively. The most stable structures for NO adsorption on a clean WO3 (001) surface and the Cu-, Ag-, and Au-deposited WO3 (001) surfaces are displayed in (f), (g), (h), and (i), respectively. In (f), (g), (h), and (i), the circle for N atom is larger than that for the O atom.

Mentions: In this work, we perform a first-principles DFT calculation to investigate the adsorption of NO molecule on a clean WO3(001) surface as well as on the noble metal atom (Cu, Ag, and Au) deposited WO3(001) surface. Here, the (001) surface (see Figure 1a,b) of γ-monoclinic WO3 is taken into account because it is the most stable at room temperature [28]. We demonstrate that the Cu-, Ag-, and Au-deposited WO3(001) surfaces exhibit different catalytic behaviors for NO adsorption, that is, the magnitude of adsorption energy (Eads) is in the order of Cu > Ag > Au. This different binding behavior of NO on WO3(001) depending on the noble metal species can be traced to the difference in charge transfer from the substrate to adsorbed NO molecule. Based on our DFT results, we will discuss the enhanced sensitivity of WO3 sensors for NO detection by employing the noble metal catalysts.Figure 1


Catalytic activities of noble metal atoms on WO3 (001): nitric oxide adsorption.

Ren X, Zhang S, Li C, Li S, Jia Y, Cho JH - Nanoscale Res Lett (2015)

Optimized atomic structure. (a) Top view and (b) side view of the clean WO3 (001) surface. The large and small circles represent W and O atoms, respectively. The most stable structures for the Cu, Ag, and Au atoms deposited on WO3 (001) surface are displayed in (c), (d), and (e), respectively. The most stable structures for NO adsorption on a clean WO3 (001) surface and the Cu-, Ag-, and Au-deposited WO3 (001) surfaces are displayed in (f), (g), (h), and (i), respectively. In (f), (g), (h), and (i), the circle for N atom is larger than that for the O atom.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
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getmorefigures.php?uid=PMC4385050&req=5

Fig1: Optimized atomic structure. (a) Top view and (b) side view of the clean WO3 (001) surface. The large and small circles represent W and O atoms, respectively. The most stable structures for the Cu, Ag, and Au atoms deposited on WO3 (001) surface are displayed in (c), (d), and (e), respectively. The most stable structures for NO adsorption on a clean WO3 (001) surface and the Cu-, Ag-, and Au-deposited WO3 (001) surfaces are displayed in (f), (g), (h), and (i), respectively. In (f), (g), (h), and (i), the circle for N atom is larger than that for the O atom.
Mentions: In this work, we perform a first-principles DFT calculation to investigate the adsorption of NO molecule on a clean WO3(001) surface as well as on the noble metal atom (Cu, Ag, and Au) deposited WO3(001) surface. Here, the (001) surface (see Figure 1a,b) of γ-monoclinic WO3 is taken into account because it is the most stable at room temperature [28]. We demonstrate that the Cu-, Ag-, and Au-deposited WO3(001) surfaces exhibit different catalytic behaviors for NO adsorption, that is, the magnitude of adsorption energy (Eads) is in the order of Cu > Ag > Au. This different binding behavior of NO on WO3(001) depending on the noble metal species can be traced to the difference in charge transfer from the substrate to adsorbed NO molecule. Based on our DFT results, we will discuss the enhanced sensitivity of WO3 sensors for NO detection by employing the noble metal catalysts.Figure 1

Bottom Line: This relatively stronger bonding of NO to the W atom is found to be associated with the larger charge transfer of 0.43 e (Cu) and 0.33 e (Ag) from the surface to adsorbed NO.On such an Au-WO3(001) complex, the NO molecule is found to form a bond to the Au atom with E ads = -1.32 eV.Because of a large electronegativity of Au atom, the adsorbed NO molecule captures the less electrons (0.04 e) from the surface compared to the Cu and Ag catalysts.

View Article: PubMed Central - PubMed

Affiliation: International Laboratory for Quantum Functional Materials of Henan, and School of Physics and Engineering, Zhengzhou University, Zhengzhou, 450001 China ; School of Mechanical and Electrical Engineering, Henan Institute of Science and Technology, Xinxiang, 453003 China.

ABSTRACT
Using first-principles density functional theory calculations within the generalized gradient approximation, we investigate the adsorption of NO molecule on a clean WO3(001) surface as well as on the noble metal atom (Cu, Ag, and Au)-deposited WO3(001) surfaces. We find that on a clean WO3 (001) surface, the NO molecule binds to the W atom with an adsorption energy (E ads) of -0.48 eV. On the Cu- and Ag-deposited WO3(001) surface where such noble metal atoms prefer to adsorb on the hollow site, the NO molecule also binds to the W atom with E ads = -1.69 and -1.41 eV, respectively. This relatively stronger bonding of NO to the W atom is found to be associated with the larger charge transfer of 0.43 e (Cu) and 0.33 e (Ag) from the surface to adsorbed NO. However, unlike the cases of Cu-WO3(001) and Ag-WO3(001), Au atoms prefer to adsorb on the top of W atom. On such an Au-WO3(001) complex, the NO molecule is found to form a bond to the Au atom with E ads = -1.32 eV. Because of a large electronegativity of Au atom, the adsorbed NO molecule captures the less electrons (0.04 e) from the surface compared to the Cu and Ag catalysts. Our findings not only provide useful information about the NO adsorption on a clean WO3(001) surface as well as on the noble metal atoms deposited WO3(001) surfaces but also shed light on a higher sensitive WO3 sensor for NO detection employing noble metal catalysts.

No MeSH data available.