原位生长n-Fe2O3/p-CaFe2O4光催化N/P异质结及光催化降解VOCs动力学研究

The semiconductor photocatalytic nanomaterials used in removing a variety of low-concentration VOCs (such as formaldehyde, acetone, benzene and other volatile organic compounds) of gaseous pollutants has attracted widespread attention. The crucial challenge of visible-light-responsive photocatalyst α-Fe2O3 is that short exciton lifetime and small diffusion length results in low photocatalytic activity. To deal with the problem, our project intends to adopt a green and controlled method with a two-step in situ synthesis of heterojunction n-Fe2O3/p-CaFe2O4 nanomaterials. In addition, the influence of the interface barrier, interface orientation at N / P heterojunction, CaFe2O4 on the distribution of Fe2O3, on the degradation kinetics of typical VOCs will be investigated; the relationship between charge separation efficiency and microstructure at interface will be revealed; the intrinsic link between N / P heterojunction characterization and photocatalytic activity will be analyzed in detail, such as heterojunction structure, semiconductor heterojunction interface component and configuration; Then using first-principles calculations to analysis heterojunction photo-induced charge transfer process and mechanism in the photocatalytic process, and establishing the corresponding theoretical model. We believe our study will provide valuable data for in-depth understanding of the intrinsic relationship between N / P heterojunction and photocatalytic activity. Furthermore, our study can not only speed up the development of new efficient photocatalyst materials but also promote its application in the field of environmental remediation and energy conversion.

半导体光催化纳米材料应用于降解去除低浓度VOCs（如甲醛，丙酮和苯类等挥发性有机物）气体污染物受到了广泛关注。针对可见光光催化剂α-Fe2O3光生载流子寿命短、空穴传输自由程短导致光催化活性低的问题，本项目拟采用绿色可控两步法原位合成新型n-Fe2O3/p-CaFe2O4异质结纳米材料。通过系统研究N/P异质结界面势垒、界面取向匹配、CaFe2O4在α-Fe2O3表面的不同分布等因素对光催化性能的影响，揭示n-Fe2O3/p-CaFe2O4异质结界面电荷分离效率与界面微结构的关系；探明异质结组分、构型、界面结构与光催化活性的内在联系；并借助第一性原理计算,对光催化过程中的光致电荷传输过程及机理进行系统分析，建立相应的理论模型。本项目的研究结果不仅对深入理解N/P光催化异质结与催化活性之间的内在联系具有重要的学术价值，还为新型高效光催化剂开发及其在环境修复与能源转化领域中应用提供新思路。

针对可见光光催化过程量子效率低而难以实现应用的重大难题，基于α-Fe2O3光生载流子寿命短和空穴传输自由程短的问题，我们采用绿色可控方法原位合成出了新型n-Fe2O3/p-CaFe2O4异质结光催化纳米粉体和薄膜材料。深入研究了简单液相法反应条件对异质结光催化纳米材料生长的调控规律；研究了这些异质结光催化剂在光催化降解有机污染物（甲醛，乙醛，苯，亚甲基蓝，罗丹名B，抗生素等）的光催化活性和光反应机理；深入研究光生电子，空穴对的迁移分离过程; 利用尖晶石结构连续固溶的特性，结合理论计算和实验，通过改变A位原子中金属比例可以实现材料禁带宽度、能带位置的连续可调；考察了半导体电极的成膜工艺对样品的光电化学性能的影响；探讨了利用Co3O4 表面修饰n-Fe2O3/p-CaFe2O4异质结再提高光电流密度并分析其作用机理；设计并成功合成了CaFe2O4/ZnFe2O4异质结。此外，通过对光半导体纳米粉体或薄膜引入氧空位方式形成缺陷能级，提高光生电子-空穴的分离率，拓宽了光谱响应范围并在多种低浓度VOCs（甲醛,苯）气体污染物光降解领域显示了优异的性能。本研究对开发新型高效光催化剂，促进太阳光光催化技术的大规模应用具有重要的理论和实际意义。