Limits...
A dye-sensitized visible light photocatalyst-Bi24O31Cl10.

Wang L, Shang J, Hao W, Jiang S, Huang S, Wang T, Sun Z, Du Y, Dou S, Xie T, Wang D, Wang J - Sci Rep (2014)

Bottom Line: Density functional theory calculations reveal that the p-block elements determine the nature of the dispersive electronic structures and narrow band gap in Bi24O31Cl10.Bi24O31Cl10 exhibits excellent visible-light photocatalytic activity towards the degradation of Rhodamine B, which is promoted by dye sensitization due to compatible energy levels and high electronic mobility.In addition, Bi24O31Cl10 is also a suitable photoanode material for dye-sensitized solar cells and shows power conversion efficiency of 1.5%.

View Article: PubMed Central - PubMed

Affiliation: Center of Materials Physics and Chemistry and Department of Physics, Beihang University, Beijing 100191, P. R. China.

ABSTRACT
The p-block semiconductors are regarded as a new family of visible-light photocatalysts because of their dispersive and anisotropic band structures as well as high chemical stability. The bismuth oxide halides belong to this family and have band structures and dispersion relations that can be engineered by modulating the stoichiometry of the halogen elements. Herein, we have developed a new visible-light photocatalyst Bi24O31Cl10 by band engineering, which shows high dye-sensitized photocatalytic activity. Density functional theory calculations reveal that the p-block elements determine the nature of the dispersive electronic structures and narrow band gap in Bi24O31Cl10. Bi24O31Cl10 exhibits excellent visible-light photocatalytic activity towards the degradation of Rhodamine B, which is promoted by dye sensitization due to compatible energy levels and high electronic mobility. In addition, Bi24O31Cl10 is also a suitable photoanode material for dye-sensitized solar cells and shows power conversion efficiency of 1.5%.

No MeSH data available.


DFT calculations of crystal and electronic structures for Bi24O31Cl10.(a)Simulated crystal structure of Bi24O31Cl10, in which Bi2O2 stacks are separated by Cl layers. Green, yellow, and red balls represent Bi, Cl, and O, respectively. (b) Calculated band structure of Bi24O31Cl10 shows a very dispersive CB structure that consists of Bi 6p and O 2p orbitals. (c) Calculated density of states (DOS) of Bi24O31Cl10 indicates a band gap of 2.20 eV.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4260216&req=5

f1: DFT calculations of crystal and electronic structures for Bi24O31Cl10.(a)Simulated crystal structure of Bi24O31Cl10, in which Bi2O2 stacks are separated by Cl layers. Green, yellow, and red balls represent Bi, Cl, and O, respectively. (b) Calculated band structure of Bi24O31Cl10 shows a very dispersive CB structure that consists of Bi 6p and O 2p orbitals. (c) Calculated density of states (DOS) of Bi24O31Cl10 indicates a band gap of 2.20 eV.

Mentions: The crystal and electronic structures are of great importance for photocatalytic properties. We carried out density functional theory (DFT) calculations to reveal the detailed electronic structures of BixOyClz compounds by tuning the stoichiometric ratio of chlorine, in order to explore potential candidate compounds for photocatalysts. Bi24O31Cl10, a compound which has a monoclinic structure with space group A12/m1 (JCPDS 75-0887)38, exhibits promising crystal and electronic structures for photocatalysis. Its crystal structure consists of stair-like [Bi,O] layers connected to the shared Cl−, as shown in Figure 1(a). The Bi, Cl, and O atoms fit into a layered stacking model. The calculated band structure and density of states (DOS) indicate that the CB of Bi24O31Cl10 mainly consists of hybridized Bi 6p and O 2p orbitals, whereas the VB is contributed by hybridized Bi 6s, Cl 3p, and O 2p orbitals, as shown in Figure 1(b) and (c). The calculations suggest that Bi24O31Cl10 is a direct-band-gap semiconductor with a gap of 2.20 eV. It is worth noting that first-principles calculations generally underestimate the band-gap value. The gap of Bi24O31Cl10 was determined to be 2.80 eV in our experiments, which confirms that this compound can absorb visible light (see the section on photocatalytic properties of Bi24O31Cl10 below). Interestingly, the bottom of the CB and the top of the VB in Bi24O31Cl10 are only constructed from p and sp states, which exactly satisfy the band requirements of p-block photocatalysts. This is evidenced by the dispersive CB and VB in Bi24O31Cl10, as shown in Figure 1(b). This gives photo-excited charge carriers small effective mass, which has benefits for charge transport under irradiation. In addition, separation of photo-induced electron-hole pairs is expected to be promoted by charge transfer from the sp-state VB and p-states CB in Bi24O31Cl10 due to orbital asymmetry in real space39. The unique crystal and electronic structures of Bi24O31Cl10 indeed lead to excellent photocatalytic performances, which have been demonstrated experimentally in this work.


A dye-sensitized visible light photocatalyst-Bi24O31Cl10.

Wang L, Shang J, Hao W, Jiang S, Huang S, Wang T, Sun Z, Du Y, Dou S, Xie T, Wang D, Wang J - Sci Rep (2014)

DFT calculations of crystal and electronic structures for Bi24O31Cl10.(a)Simulated crystal structure of Bi24O31Cl10, in which Bi2O2 stacks are separated by Cl layers. Green, yellow, and red balls represent Bi, Cl, and O, respectively. (b) Calculated band structure of Bi24O31Cl10 shows a very dispersive CB structure that consists of Bi 6p and O 2p orbitals. (c) Calculated density of states (DOS) of Bi24O31Cl10 indicates a band gap of 2.20 eV.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4260216&req=5

f1: DFT calculations of crystal and electronic structures for Bi24O31Cl10.(a)Simulated crystal structure of Bi24O31Cl10, in which Bi2O2 stacks are separated by Cl layers. Green, yellow, and red balls represent Bi, Cl, and O, respectively. (b) Calculated band structure of Bi24O31Cl10 shows a very dispersive CB structure that consists of Bi 6p and O 2p orbitals. (c) Calculated density of states (DOS) of Bi24O31Cl10 indicates a band gap of 2.20 eV.
Mentions: The crystal and electronic structures are of great importance for photocatalytic properties. We carried out density functional theory (DFT) calculations to reveal the detailed electronic structures of BixOyClz compounds by tuning the stoichiometric ratio of chlorine, in order to explore potential candidate compounds for photocatalysts. Bi24O31Cl10, a compound which has a monoclinic structure with space group A12/m1 (JCPDS 75-0887)38, exhibits promising crystal and electronic structures for photocatalysis. Its crystal structure consists of stair-like [Bi,O] layers connected to the shared Cl−, as shown in Figure 1(a). The Bi, Cl, and O atoms fit into a layered stacking model. The calculated band structure and density of states (DOS) indicate that the CB of Bi24O31Cl10 mainly consists of hybridized Bi 6p and O 2p orbitals, whereas the VB is contributed by hybridized Bi 6s, Cl 3p, and O 2p orbitals, as shown in Figure 1(b) and (c). The calculations suggest that Bi24O31Cl10 is a direct-band-gap semiconductor with a gap of 2.20 eV. It is worth noting that first-principles calculations generally underestimate the band-gap value. The gap of Bi24O31Cl10 was determined to be 2.80 eV in our experiments, which confirms that this compound can absorb visible light (see the section on photocatalytic properties of Bi24O31Cl10 below). Interestingly, the bottom of the CB and the top of the VB in Bi24O31Cl10 are only constructed from p and sp states, which exactly satisfy the band requirements of p-block photocatalysts. This is evidenced by the dispersive CB and VB in Bi24O31Cl10, as shown in Figure 1(b). This gives photo-excited charge carriers small effective mass, which has benefits for charge transport under irradiation. In addition, separation of photo-induced electron-hole pairs is expected to be promoted by charge transfer from the sp-state VB and p-states CB in Bi24O31Cl10 due to orbital asymmetry in real space39. The unique crystal and electronic structures of Bi24O31Cl10 indeed lead to excellent photocatalytic performances, which have been demonstrated experimentally in this work.

Bottom Line: Density functional theory calculations reveal that the p-block elements determine the nature of the dispersive electronic structures and narrow band gap in Bi24O31Cl10.Bi24O31Cl10 exhibits excellent visible-light photocatalytic activity towards the degradation of Rhodamine B, which is promoted by dye sensitization due to compatible energy levels and high electronic mobility.In addition, Bi24O31Cl10 is also a suitable photoanode material for dye-sensitized solar cells and shows power conversion efficiency of 1.5%.

View Article: PubMed Central - PubMed

Affiliation: Center of Materials Physics and Chemistry and Department of Physics, Beihang University, Beijing 100191, P. R. China.

ABSTRACT
The p-block semiconductors are regarded as a new family of visible-light photocatalysts because of their dispersive and anisotropic band structures as well as high chemical stability. The bismuth oxide halides belong to this family and have band structures and dispersion relations that can be engineered by modulating the stoichiometry of the halogen elements. Herein, we have developed a new visible-light photocatalyst Bi24O31Cl10 by band engineering, which shows high dye-sensitized photocatalytic activity. Density functional theory calculations reveal that the p-block elements determine the nature of the dispersive electronic structures and narrow band gap in Bi24O31Cl10. Bi24O31Cl10 exhibits excellent visible-light photocatalytic activity towards the degradation of Rhodamine B, which is promoted by dye sensitization due to compatible energy levels and high electronic mobility. In addition, Bi24O31Cl10 is also a suitable photoanode material for dye-sensitized solar cells and shows power conversion efficiency of 1.5%.

No MeSH data available.