Zheng Hongchun, Wang Jincheng, Kong Bo, Xu Xiang, Zhang Min, Wang Wentao
School of Physics and Astronomy, China West Normal University, Nanchong 637002, China.
Guizhou Provincial Key Laboratory of Computational Nano-Material Science, Guizhou Education University, Guiyang, 550018, China.
Phys Chem Chem Phys. 2023 Nov 22;25(45):30848-30857. doi: 10.1039/d3cp03636g.
In this work, the intrinsic point defect properties of bulk BiPO under different growth conditions are intensively investigated and explored using first-principles hybrid functional calculations. It is found that Bi vacancies and O vacancies are the primary native defects in BiPO. Under O-poor conditions, BiPO acts as an intrinsic insulator because the O vacancy defects (donor) and the Bi vacancy defects (acceptor) compensate for each other. Under Bi-poor conditions, good p-type conductivity is observed in BiPO, which affirms the observed p-type conductivity behavior in experiments. Bi vacancies in BiPO are very shallow, which make it an excellent acceptor and are mostly responsible for the p-type character. In addition, it is found that the primary Bi vacancy defects of BiPO hardly affect its electronic structure and optical absorption spectrum regardless of the charge states. In contrast, the neutral O vacancy defects in BiPO introduce an impurity energy level near the VBM and induce a new optical absorption peak at around 370 nm. Furthermore, the O vacancies should be favorable for enhancing the production and separation efficiencies of the photo-generated electrons and holes in BiPO. While Bi vacancies easily provide p-type carriers, simultaneously, they could become the active sites for the photocatalytic reactions because of their dominant -3 charge state. Therefore, understanding the defect physics in BiPO photocatalysts is believed to be beneficial for more research in developing BiPO or BiPO-based photocatalysts.
在这项工作中，我们使用第一性原理混合泛函计算方法，深入研究和探索了不同生长条件下块状磷酸铋（BiPO）的本征点缺陷性质。研究发现，铋空位和氧空位是BiPO中的主要本征缺陷。在贫氧条件下，BiPO表现为一种本征绝缘体，因为氧空位缺陷（施主）和铋空位缺陷（受主）相互补偿。在贫铋条件下，BiPO中观察到良好的p型导电性，这证实了实验中观察到的p型导电行为。BiPO中的铋空位非常浅，这使其成为一种优良的受主，并且对p型特性起主要作用。此外，研究发现，BiPO的主要铋空位缺陷无论其电荷状态如何，几乎都不会影响其电子结构和光吸收光谱。相比之下，BiPO中的中性氧空位缺陷在价带顶附近引入了一个杂质能级，并在370nm左右诱导出一个新的光吸收峰。此外，氧空位应该有利于提高BiPO中光生电子和空穴的产生及分离效率。虽然铋空位很容易提供p型载流子，但同时，由于其占主导的 -3 电荷状态，它们可能成为光催化反应的活性位点。因此，了解BiPO光催化剂中的缺陷物理性质，被认为有助于开展更多关于开发BiPO或基于BiPO的光催化剂的研究。
