多壳层空心结构钙钛矿催化剂的可控制备及光解水性能的研究

Hydrogen production by photocatalytic water splitting is one of the most important ways to exploit and utilize hydrogen energy. The existing photocatalysts have a series of problems including material single variety, high cost, low efficiency, which inhibit their application. Therefore, the development of novel photocatalyst with high efficiency and low cost has great importance in scientific purpose and application value. In this project, the advantages of multi-shelled hollow structure materials（RbLnM2O7，Ln=La，Ce; M=Nb，Ta） including higher specific surface area and more active sites are utilized to design and synthesis of multi-shelled hollow structure perovskite nano-materials with high catalytic performance and excellent cycle stability and construct an efficient and new type of photocatalytic water splitting system by taking the research of high efficiency perovskite photo-catalyst as the breakthrough point. The controlled synthesis of perovskite photocatalytic materials with multi-sheledl hollow structure is realized by template method and extra-fields intensifying. Besides, the regulation rules of the multi-shelled structure including the number of shells, shell thickness, shell spacing, etc. in the synthesis process are systematically analyzed. The influence of material structure on the photocatalytic properties is deeply researched and the transmission path of the photo-generated electrons and holes in the multi-shelled hollow structure will be explored. Combined with theoretical calculation, the structure-activity relationship between the multi-shelled structure and photocatalytic performance is revealed and the reaction mechanism is clearly clarified. On the whole, the implementation of this project will provide a theoretical and experimental basis for the development of new perovskite catalytic materials for water splitting.

光解水制氢是开发利用氢能的重要途径，现有光催化剂存在材料单一、效率较低等问题，限制了实际应用，因此，研发新型高效光催化剂具有重要的科学意义和应用价值。本项目以高效钙钛矿光催化剂（RbLnM2O7，Ln=La，Ce; M=Nb，Ta）的研发为切入点，利用多壳层空心结构比表面积大，活性位点多等优点，旨在设计与合成催化性能高，循环稳定性好的多壳层空心结构钙钛矿纳米材料，构建高效的新型光催化分解水体系。通过模板法与外场强化相结合的手段实现多壳层空心结构钙钛矿光催化材料的可控合成，并将系统地分析合成过程中多壳层结构的壳层数目、壳层厚度、壳层间距等参数的调控规律；深入研究材料结构对光催化性能的影响；探究光生电子与空穴在多壳层空心结构中的传输路径；结合理论计算，揭示多壳层结构与光催化性能的构效关系，阐明反应机理。本项目的实施将为新型钙钛矿催化材料光解水的研发提供实验基础和理论依据。

本项目以多壳层空心结构催化剂材料的可控制备为目标，采用“次序模板法”，通过加强吸附、提高扩散效率以及优化程序升温等外场强化方法实现对多壳层空心结构光催化材料的组成、结构及形貌的调控，特别是对该光催化材料带隙的调控和光捕获性能的调控。确定最佳合成条件，成功合成了SrTiO3:La, Rh等一系列多壳层空心结构钙钛矿型光催化剂，Nb2O5单、双、三壳层空心球以及SnS2/SnO2异质结构多壳层空心球结构材料。经过光催化分解水系统的测试，负载了助催化剂的SrTiO3-TiO2 中空多壳层结构（HoMSs）能够稳定的以化学计量比分解纯水。得益于钙钛矿SrTiO3稳定的结构，该光催化剂能够保持1天以上的循环稳定性。该研究表明将多壳层中空结构引入钙钛矿型SrTiO3光催化剂中能够有效地提高其光捕获性能和光催化活性。1.经过光催化分解水系统的测试，负载了助催化剂的SrTiO3-TiO2 中空多壳层结构（HoMSs）能够稳定的以化学计量比分解纯水。得益于钙钛矿SrTiO3稳定的结构，该光催化剂能够保持1天以上的循环稳定性。该研究表明将多壳层中空结构引入钙钛矿型SrTiO3光催化剂中能够有效地提高其光捕获性能和光催化活性。2.制备了单、双、三壳层Nb2O5 HoMSs，中空多壳层这种特殊的结构具有丰富的表面多孔结构，大的有效比表面积，多层空腔的结构特点，这种结构不但有利于光生电子的快速传输，内外壳壁会增大活性材料的有效接触面积，提供更多的活性位点，从而达到改善Nb2O5性能的目的。3.合成了SnS2/SnO2异质结构多壳层中空球。光催化性能测试结果显示随着壳层数的增加，光催化还原性能逐步增加，四壳层中空球的光催化性能最高，并且表现出最好的光吸收性，而纳米粒子的光吸收能力是最差的。这是因为在多壳层中空球中，光可以在中空球内部发生多级散/反射，继而大大增加对光的吸收，而对于纳米粒子来说，光入射到催化剂上，相当一部分的光被反射掉，大大消弱了其对光的吸收。从光催化性能测试结果可以表明催化剂的活性并不是一定与其比表面积成正相关，而与催化剂的形貌有着至关重要的关系。