An atomic insight into BiOBr/La2Ti2O7 p–n heterojunctions: interfacial charge transfer pathway and photocatalysis mechanism,Catalysis Science & Technology

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An atomic insight into BiOBr/La2Ti2O7 p–n heterojunctions: interfacial charge transfer pathway and photocatalysis mechanism
Catalysis Science & Technology ( IF 4.4 ) Pub Date : 2019/12/16 , DOI: 10.1039/c9cy02230a
Huizhong Wu _{1,

2,

3,

4,

5} , Ruimin Chen _{1,

2,

3,

4,

5} , Hong Wang _{5,

6,

7,

8,

9} , Wen Cui _{1,

2,

3,

4,

5} , Jieyuan Li _{5,

6,

7,

8,

9} , Jiadong Wang _{1,

2,

3,

4,

5} , Chaowei Yuan _{1,

2,

3,

4,

5} , Lin Zhuo _{1,

2,

3,

4,

5} , Yuxin Zhang _{5,

10,

11,

12} , Fan Dong _{1,

2,

3,

4,

5}

Affiliation

Novel p–n heterojunction BiOBr/La₂Ti₂O₇ nanocomposites were synthesized through a hydrothermal method and applied to photocatalytic NO removal. The reaction course of visible light photocatalytic NO removal was dynamically monitored by in situ FT-IR, and free radicals were captured by electron spin resonance (ESR). The reaction mechanism of photocatalytic NO oxidation on BiOBr/La₂Ti₂O₇ was revealed. Density functional theory (DFT) calculations show that when BiOBr comes into contact with La₂Ti₂O₇ to form a p–n heterojunction, the charge could transfer from the La atom of La₂Ti₂O₇ to the O atom of BiOBr, leading to the accumulation of negative charge in the BiOBr region. When the Fermi levels of BiOBr and La₂Ti₂O₇ are in equilibrium, an internal electric field (IEF) from La₂Ti₂O₇ to BiOBr is established simultaneously. Under visible light illumination, the photogenerated electrons (e⁻) in the conduction band (CB) of BiOBr would migrate to the CB of La₂Ti₂O₇ with the assistance of the IEF, and the holes (h⁺) are gathered on the valence band (VB) of BiOBr. With this IEF, the charge carrier separation on BiOBr/La₂Ti₂O₇ was highly promoted and thus the visible light photocatalytic NO removal performance was enhanced. This work provides a new perspective on the understanding of the construction mechanism of p–n type heterostructures and the mechanism of gas–solid phase photocatalytic reactions.

中文翻译：

BiOBr / La2Ti2O7 p–n异质结的原子洞察：界面电荷转移途径和光催化机制

通过水热法合成了新型的p-n异质结BiOBr / La ₂ Ti ₂ O ₇纳米复合材料，并将其用于光催化脱除NO。通过原位FT-IR动态监测可见光光催化脱氮的反应过程，并通过电子自旋共振（ESR）捕获自由基。揭示了BiOBr / La ₂ Ti ₂ O ₇上光催化NO氧化的反应机理。密度泛函理论（DFT）计算表明，当BiOBr与La ₂ Ti ₂ O ₇接触形成ap–n异质结时，电荷可能从La的La原子转移在BiOBr的O原子上形成₂ Ti₂ O₇，导致BiOBr区域中负电荷的积累。当BiOBr和La₂ Ti₂ O₇的费米能级处于平衡状态时，会同时建立从La₂ Ti₂ O₇到BiOBr的内部电场（IEF）。在可见光下的照明，光生电子（e^-）在BiOBr的导带（CB）将迁移〜La的CB₂的Ti₂ ö₇与IEF的协助下，和空穴（h⁺）聚集在BiOBr的价带（VB）上。利用该IEF，大大促进了BiOBr / La ₂ Ti ₂ O ₇上的载流子分离，从而提高了可见光光催化NO去除性能。这项工作为对p-n型异质结构的构造机理和气相-固相光催化反应机理的理解提供了新的视角。

更新日期：2020-02-13

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