面-面结合型BaTiO3/g-C3N4基异质结的构筑及压电-光催化机制研究

Photocatalytic technology is an effective way to solve the problem of water pollution. Aiming at the widely existing problem of poor visible light respond, low catalytic efficiency and difficult recovery in current photocatalytic materials, this project is based on the piezo-photocatalytic principle, starts from the view of configuration optimization and internal electric field regulation, proposes the new idea of constructing the face-to-face combined BaTiO3/g-C3N4 based heterojunction, improving the polarization electric field and increasing the photocatalytic efficiency by inducing the extrinsic piezoelectric response of piezoelectric phase. Through the finite element simulation, the heterojunction with larger polarization electric field is obtained. Through the condensation reaction of the surface hydroxyl groups, the stability of the face-to-face combined heterojunction is increased. Through composition regulation of the piezoelectric phase and the pre-polarization of the heterojunction, polarization electric field of heterojunction is improved. Eventually, the relationship between the piezoelectric phase and the semiconductor phase’s size， morphology and the effective polarization electric field of the heterojunction is elucidated. The function mechanism between the interface bond and the stability of heterojunction, the function mechanism between the interface bond and the catalytic performance are revealed. The intrinsic improvement mechanism of the polarized electric field and interfacial electric field to photocatalytic performance is clarified. The theoretical model for the simultaneous improvement of the photocatalytic properties of intrinsic and extrinsic piezoelectric responses is established. The results will not only provide a theoretical basis for further understanding of the piezo-photocatalytic mechanism, but also provide theoretical guidance for the design of highly efficient photocatalytic materials and the practical application of photocatalytic technology.

光催化技术是解决水污染难题的有效途径，针对现有光催化材料普遍存在的可见光响应差、催化效率低、稳定性差等问题，本项目利用压电-光催化原理，从构型优化与内建电场调控的角度出发，提出了构筑面-面结合型BaTiO3/g-C3N4基异质结，并通过诱导压电相的非本征压电响应提高极化电场、增加光催化效率的新思路。通过有限元模拟，获得极化电场较大的异质结构型；通过表面羟基的缩合反应，增加面-面结合型异质结的稳定性；通过调控压电相的成分与外加电场预极化，提高异质结的极化电场。最终阐明压电相、半导体相的尺寸、形貌与异质结中有效极化电场的关系，揭示界面结合键对异质结及催化性能稳定性的作用机理，明确极化电场与界面电场协同改善光催化性能的内在机制，建立本征与非本征压电响应共同改善光催化性能的理论模型。所得研究结果将不仅为压电-光催化技术提供基础理论支撑，而且为高效光催化材料的设计和光催化技术的实际应用提供参考。

光催化技术是解决水污染难题的有效途径，针对现有光催化材料普遍存在的可见光响应差、催化效率低、稳定性差等问题，本项目利用压电-光催化原理，从构型优化与内建电场调控的角度出发，提出了构筑面面结合型BaTiO3/g-C3N4基异质结，并通过诱导压电相的非本征压电响应提高极化电场、增加光催化效率的新思路。通过有限元模拟，获得极化电场较大的BaTiO3构型，为异质结中单相选择提供理论依据；通过实验制备不同形貌和尺寸的BaTiO3，研究其各自的压电-催化性能，并与理论模拟相对比；通过表面羟基的缩合反应，构筑不同配比的BaTiO3/g-C3N4异质结，研究BaTiO3含量对异质结压电-催化性能的影响。本项目研究证实，大的长径比有利于提高压电相的压电-催化性能；BaTiO3纳米纤维的催化性能明显优于纳米颗粒，Ba(OH)2与K2Ti4O9的比例为分别为1:1，反应温度为140 oC时，所得BaTiO3纳米纤维的形貌和催化性能均最好；60 nm粒径的BaTiO3其压电-催化性能优于100 nm的BaTiO3纳米颗粒，且前者和g-C3N4复合之后的异质结催化性能仍然优于后者；对于两种粒径的BaTiO3/g-C3N4异质结，当BaTiO3含量为80%时异质结性能最优。本项目阐明了压电相的尺寸、形貌与异质结中有效极化电场的关系，揭示了界面结合键对异质结及催化性能稳定性的作用机理，明确了极化电场与界面电场协同改善光催化性能的内在机制，建立了本征与非本征压电响应共同改善光催化性能的理论模型。所得研究结果将不仅为压电光催化技术提供基础理论支撑，而且为高效光催化材料的设计和光催化技术的实际应用提供参考。