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SiH/TiO2 and GeH/TiO2 heterojunctions: promising TiO2-based photocatalysts under visible light.

Niu M, Cheng D, Cao D - Sci Rep (2014)

Bottom Line: The band gap of the SiH/TiO2(101) heterojunction is 2.082 eV, which is an ideal material for the visible-light photoexcitation of electron-hole pairs.Furthermore, the SiH/TiO2(101) heterojunction has a favorable type-II band alignment and thus the photoexcited electron can be injected to the conduction band of anatase TiO2 from that of silicane.Our calculation results suggest that such electronic structure of SiH/TiO2(101) heterojunction has significant advantages over these of doped TiO2 systems for visible-light photocatalysis.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029, P. R. China.

ABSTRACT
We use hybrid density functional calculations to find that the monolayer silicane (SiH) and the anatase TiO2(101) composite (i.e. the SiH/TiO2 heterojunction) is a promising TiO2-based photocatalyst under visible light. The band gap of the SiH/TiO2(101) heterojunction is 2.082 eV, which is an ideal material for the visible-light photoexcitation of electron-hole pairs. Furthermore, the SiH/TiO2(101) heterojunction has a favorable type-II band alignment and thus the photoexcited electron can be injected to the conduction band of anatase TiO2 from that of silicane. Finally, the proper interface charge distribution facilitates the carrier separation in the SiH/TiO2(101) interface region. The electron injection and carrier separation can prevent the recombination of electron-hole pairs. Our calculation results suggest that such electronic structure of SiH/TiO2(101) heterojunction has significant advantages over these of doped TiO2 systems for visible-light photocatalysis.

No MeSH data available.


Related in: MedlinePlus

Structures of monolayer silicane, germanane, and two-layer anatase TiO2(101) surface.The top and side views of monolayer (a) silicane, (b) germanane, and (c) two-layer anatase TiO2(101) slabs, respectively, a and b are the lattice constants and h represents the height of monolayer silicane and germanane. The yellow, green, white, grey, and red balls represent Si, Ge, H, Ti, and O atoms, respectively.
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f1: Structures of monolayer silicane, germanane, and two-layer anatase TiO2(101) surface.The top and side views of monolayer (a) silicane, (b) germanane, and (c) two-layer anatase TiO2(101) slabs, respectively, a and b are the lattice constants and h represents the height of monolayer silicane and germanane. The yellow, green, white, grey, and red balls represent Si, Ge, H, Ti, and O atoms, respectively.

Mentions: The chair-like monolayer silicane and germanane are graphene-like hexagonal sheets with the hydrogen atoms alternating on both sides of the Si and Ge planes, as shown in Figure 1(a) and Figure 1(b), respectively. The optimized lattice parameters are a = 3.888 Å, h = 3.721 Å and a = 4.085 Å, h = 3.859 Å for monolayer silicane and germanane, respectively. Here, we choose anatase TiO2(101) surface as substrate to support monolayer silicane and germanane because the TiO2(101) surface is the most stable surface among the low index surfaces of anatase TiO2. More importantly, a 2 × 2 unit cell of anatase TiO2(101) has a rectangular cell of 20.820 Å × 7.641 Å, which is nicely matched with a 5 × rectangular unit cell of monolayer silicane or germanane. The SiH/TiO2(101) and GeH/TiO2(101) heterojunctions were modeled by placing the monolayer silicane and germanane sheets on the top of two-layer anatase TiO2(101) slabs, respectively. The structure of 2 × 2 unit cell of two-layer anatase TiO2(101) slab is displayed in Figure 1(c). Such a slab model has been used often for theoretical calculations212627. A vacuum region of 20 Å above TiO2(101) slabs in SiH/TiO2(101) and GeH/TiO2(101) heterojunctions was used to minimize the interactions between neighboring systems.


SiH/TiO2 and GeH/TiO2 heterojunctions: promising TiO2-based photocatalysts under visible light.

Niu M, Cheng D, Cao D - Sci Rep (2014)

Structures of monolayer silicane, germanane, and two-layer anatase TiO2(101) surface.The top and side views of monolayer (a) silicane, (b) germanane, and (c) two-layer anatase TiO2(101) slabs, respectively, a and b are the lattice constants and h represents the height of monolayer silicane and germanane. The yellow, green, white, grey, and red balls represent Si, Ge, H, Ti, and O atoms, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4007092&req=5

f1: Structures of monolayer silicane, germanane, and two-layer anatase TiO2(101) surface.The top and side views of monolayer (a) silicane, (b) germanane, and (c) two-layer anatase TiO2(101) slabs, respectively, a and b are the lattice constants and h represents the height of monolayer silicane and germanane. The yellow, green, white, grey, and red balls represent Si, Ge, H, Ti, and O atoms, respectively.
Mentions: The chair-like monolayer silicane and germanane are graphene-like hexagonal sheets with the hydrogen atoms alternating on both sides of the Si and Ge planes, as shown in Figure 1(a) and Figure 1(b), respectively. The optimized lattice parameters are a = 3.888 Å, h = 3.721 Å and a = 4.085 Å, h = 3.859 Å for monolayer silicane and germanane, respectively. Here, we choose anatase TiO2(101) surface as substrate to support monolayer silicane and germanane because the TiO2(101) surface is the most stable surface among the low index surfaces of anatase TiO2. More importantly, a 2 × 2 unit cell of anatase TiO2(101) has a rectangular cell of 20.820 Å × 7.641 Å, which is nicely matched with a 5 × rectangular unit cell of monolayer silicane or germanane. The SiH/TiO2(101) and GeH/TiO2(101) heterojunctions were modeled by placing the monolayer silicane and germanane sheets on the top of two-layer anatase TiO2(101) slabs, respectively. The structure of 2 × 2 unit cell of two-layer anatase TiO2(101) slab is displayed in Figure 1(c). Such a slab model has been used often for theoretical calculations212627. A vacuum region of 20 Å above TiO2(101) slabs in SiH/TiO2(101) and GeH/TiO2(101) heterojunctions was used to minimize the interactions between neighboring systems.

Bottom Line: The band gap of the SiH/TiO2(101) heterojunction is 2.082 eV, which is an ideal material for the visible-light photoexcitation of electron-hole pairs.Furthermore, the SiH/TiO2(101) heterojunction has a favorable type-II band alignment and thus the photoexcited electron can be injected to the conduction band of anatase TiO2 from that of silicane.Our calculation results suggest that such electronic structure of SiH/TiO2(101) heterojunction has significant advantages over these of doped TiO2 systems for visible-light photocatalysis.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029, P. R. China.

ABSTRACT
We use hybrid density functional calculations to find that the monolayer silicane (SiH) and the anatase TiO2(101) composite (i.e. the SiH/TiO2 heterojunction) is a promising TiO2-based photocatalyst under visible light. The band gap of the SiH/TiO2(101) heterojunction is 2.082 eV, which is an ideal material for the visible-light photoexcitation of electron-hole pairs. Furthermore, the SiH/TiO2(101) heterojunction has a favorable type-II band alignment and thus the photoexcited electron can be injected to the conduction band of anatase TiO2 from that of silicane. Finally, the proper interface charge distribution facilitates the carrier separation in the SiH/TiO2(101) interface region. The electron injection and carrier separation can prevent the recombination of electron-hole pairs. Our calculation results suggest that such electronic structure of SiH/TiO2(101) heterojunction has significant advantages over these of doped TiO2 systems for visible-light photocatalysis.

No MeSH data available.


Related in: MedlinePlus