Cui Yongfei, Guo Peng, Wang Fenghui, Dang Peipei, Wang Cuicui, Jing Panpan, Pu Yongping, Tao Xiaoma
School of Materials Science and Engineering, Shaanxi Key Laboratory of Green Preparation and Functionalization for Inorganic Materials, Shaanxi University of Science &Technology, Xi'an710021, Shaanxi, P. R. China.
School of Physics and Technology, Guangxi University, Nanning530004, Guangxi, P. R. China.
ACS Appl Mater Interfaces. 2022 Nov 23;14(46):51819-51834. doi: 10.1021/acsami.2c12026. Epub 2022 Nov 9.
Constructing facet junction in semiconductor photocatalysts has been demonstrated as an effective method to promote charge-carrier separation and suppress carrier recombination. Herein, we proposed a novel but facile self-doping strategy to regulate the crystal facet exposure ratio in ferroelectric BiTiNbO single-crystalline nanosheets, thereby optimizing its facet junction effect. Through tuning the atomic ratio of Ti and Nb, the exposure ratio of {001} and {110} crystal planes in BiTiNbO nanosheets can be delicately modulated, and more {110} facets were exposed with the increase of the Ti/Nb atomic ratio as evidenced by the X-ray diffraction and scanning electron microscopy results. A facet junction between {110} and {001} crystal planes was verified based on the density functional theory calculation and photodeposition experiment results. Photogenerated electrons tend to accumulate in {110}, while holes gathered in {001} crystal planes. Owing to the optimal facet junction effect, the sample of Ti1.05 shows the most efficient charge-carrier separation and transportation compared to Ti0.95 and Ti1.00 as supported by the photoluminescence, surface photovoltage, photoelectrochemistry, and electron paramagnetic resonance (EPR) results. In addition, the oxygen vacancy arising from the inequivalent substitution of Nb by Ti as proved by X-ray photoelectron spectroscopy and EPR results and the enhanced ferroelectricity supported by - loops can also assist charge-carrier separation and migration. Benefiting from these properties, Ti1.05 outperformed Ti0.95 and Ti1.00 in the photodegradation of organic dye and antibiotic molecules. Meanwhile, the excellent antibacterial activity of Ti1.05 under visible light was also demonstrated by the sterilization experiment. This work not only presents a novel pathway to adjust the facet junction but also provides new deep insights into the crystal facet engineering in ferroelectrics as photocatalysts.
在半导体光催化剂中构建晶面结已被证明是促进电荷载流子分离和抑制载流子复合的有效方法。在此，我们提出了一种新颖且简便的自掺杂策略，以调节铁电BiTiNbO单晶纳米片中晶面的暴露比例，从而优化其晶面结效应。通过调整Ti和Nb的原子比，可以精细地调节BiTiNbO纳米片中{001}和{110}晶面的暴露比例，并且随着Ti/Nb原子比的增加，更多的{110}面被暴露，X射线衍射和扫描电子显微镜结果证明了这一点。基于密度泛函理论计算和光沉积实验结果，验证了{110}和{001}晶面之间的晶面结。光生电子倾向于在{110}面积累，而空穴聚集在{001}晶面。由于最佳的晶面结效应，与Ti0.95和Ti1.00相比，Ti1.05样品表现出最有效的电荷载流子分离和传输，光致发光、表面光电压、光电化学和电子顺磁共振（EPR）结果支持了这一点。此外，X射线光电子能谱和EPR结果证明，Ti对Nb的不等价取代产生的氧空位以及 - 回线支持的增强铁电性也有助于电荷载流子的分离和迁移。受益于这些特性，Ti1.05在有机染料和抗生素分子的光降解方面优于Ti0.95和Ti1.00。同时，杀菌实验也证明了Ti1.05在可见光下具有优异的抗菌活性。这项工作不仅为调节晶面结提供了一条新途径，还为铁电体作为光催化剂的晶面工程提供了新的深刻见解。
