Mechanisms of interfacial charge transfer and photocatalytic NO oxidation on BiOBr/SnO2 p-n heterojunctions.
Mechanisms of interfacial charge transfer and photocatalytic NO oxidation on BiOBr/SnO2 p-n heterojunctions.
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DOI：
10.1021/acsami.0c12628
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发表时间：
2020-09
影响因子：
9.5
通讯作者：
Huizhong Wu;Chaowei Yuan;Ruimin Chen;Jiadong Wang;F. Dong;Jieyuan Li;Yanjuan Sun
中科院分区：
文献类型：
--
作者：
Huizhong Wu;Chaowei Yuan;Ruimin Chen;Jiadong Wang;F. Dong;Jieyuan Li;Yanjuan Sun
本文采用水热法制备了p-n异质结BiOBr/SnO2光催化剂，并将其应用于可见光下去除NO。所合成的BiOBr/SnO2光催化剂通过建立p-n异质结表现出优异的光催化活性和稳定性，从而显著改善了电荷分离和转移性能。对BiOBr/SnO2异质结的形态结构和光学性能进行了全面的研究。BiOBr和SnO2之间构建的异质结通过在BiOBr微球表面涂覆SnO2将光吸收扩展到可见光范围，从而在可见光下实现高效的NO去除。此外，通过实验研究和理论计算相结合的方法确定了BiOBr/SnO2界面处的电荷转移通道和方向。在p-n异质结内，SnO2中的电荷通过预先形成的电子转移通道迁移到BiOBr中，从而产生从SnO2到BiOBr的内部电场（IEF）。BiOBr的光生电子在IEF的作用下从传导带（CB）转移到SnO2的传导带（CB），从而促进了电子(e-) -空穴（h+）对的分离。利用原位漂移技术对可见光NO去除过程中的中间体和最终产物进行了监测，合理地提出了NO的氧化途径。同时，异质结的构建不仅实现了更高效的NO光催化氧化，还抑制了毒性更强的NO2的产生。这项工作为异质结光催化剂的界面电荷转移和高效空气净化的反应机理提供了机理上的见解。
In this work, p-n heterojunction BiOBr/SnO2 photocatalysts were prepared by a hydrothermal method and applied to eliminate NO under visible light irradiation. The as-synthesized BiOBr/SnO2 photocatalysts exhibit superior photocatalytic activity and stability through the establishment of p-n heterojunction, which results in significantly improved charge separation and transfer properties. The morphological structure and optical property of BiOBr/SnO2 heterojunction were also investigated comprehensively. The constructed heterojunction between BiOBr and SnO2 extends the light absorption into the visible range by SnO2 coated on the surface of the BiOBr microsphere, thus achieving efficient NO removal under visible light. Moreover, the charge transfer channels and direction at the BiOBr/SnO2 interface were determined by means of combined experimental investigations and theoretical calculations. within this p-n heterojunction, the charge in SnO2 migrates into BiOBr through the pre-formed electron transfer channels, thus generating an internal electric field (IEF) from SnO2 to BiOBr. The photogenerated electrons of BiOBr is transferred from the conduction band (CB) to the CB of SnO2 under the influence of the IEF, thus facilitating the separation of electrons (e-) - holes (h+) pairs. The intermediates and final products during visible light NO removal were monitored by in situ DRIFTS technology, hence the oxidation pathways of NO were reasonably proposed. Meanwhile, the construction of heterojunction not only achieves more efficient NO photocatalytic oxidation but also inhibits the production of more toxic NO2. This work provides mechanistic insights into the interfacial charge transfer for heterojunction photocatalysts and reaction mechanism for efficient air purification.