宏观三维C-dots/Ta3N5纳米孔材料的可控构筑及其光催化全分解水性能研究

Solar-driven water splitting is one of the most promising ways to convert solar energy into chemical energy, especially hydrogen, a storable fuel. The ultimate target of photocatalytic water splitting is to explore novel efficient, stable and broad spectra response photocatalysts. Tantalum nitride (Ta3N5), as a narrow bandgap semiconductor photocatalyst with an absorption edge around 600 nm, suffers from the high recombination of the photoexcited carriers and photo-corrosion, which limits its practical applications. In this proposal, we aim to use 3D porous g-C3N4 nanosponges as both template and nitrogen source to fabricate C dots/Ta3N5 nanocomposites photocatalyst with high specific surface area and being easily recycled. Their performances of hydrogen and oxygen production from solar overall water splitting are also investigated. More significantly, the effects of C dots on the solar utilization, charge carrier migration and separation, the suppressing of self-oxidation of Ta3N5, as well as the decomposition of H2O2 will be disclosed. We will pay our great attention on the fundamental scientific events of such new-type C dots/Ta3N5 photocatalytic systems, including the electron/energy transfer/transport principles during their photocatalytic processes, the reaction mechanism of overall water splitting, etc. Our work will provide the scientific guidelines for rational design and controllable fabrication of solar water splitting photocatalyst with high apparent quantum yield in the wavelength range of 550-650 nm.

利用太阳光驱动水分解是将太阳能转化为化学能、特别是氢能的最有效策略之一。设计合成新型高效、稳定长效且宽光谱响应的光催化剂成为太阳光驱动水分解技术得以广泛应用的关键所在。作为吸收边在600nm左右的窄带隙半导体光催化材料，Ta3N5光生载流子复合率高及易发生光腐蚀等缺点极大地限制了其实际应用。本项目拟以具有丰富孔结构的g-C3N4纳米海绵为模板和氮源，可控制备高比表面积且易回收的宏观三维Cdots/Ta3N5复合纳米光催化剂，研究其太阳光分解水产氢产氧的性能。揭示C量子点在提高太阳光吸收与利用率、促进光生载流子的传递与分离、抑制Ta3N5自氧化以及促进H2O2分解历程中的作用机制，探究催化过程中电子/能量的转移/传输规律与机制，阐明Cdots/Ta3N5光催化全解水的反应机理等重要科学问题，为理性设计与可控构筑550-650nm波长范围内高量子产率的全解水光催化剂提供科学指导。

半导体光催化分解水制氢是当前解决环境污染和能源危机最富有前景的方法，是太阳能利用最理想的方式之一。这项技术的关键是开发高效稳定、环境友好的可见光催化剂。本项目在国家自然科学基金的支持下，设计构筑了多种基于Ta3N5半导体的催化剂体系，其中包括二维介孔Ta3N5、Type II型Ta3N5/SrTaO2N异质结以及Ta3N5/Bi/CaTaO2N全固态Z型异质结催化剂，在模拟太阳光下对所合成的催化剂进行了光催化分解水性能研究，取得了一系列创新性成果。研究结果表明，微观结构调控以及构筑界面“结”工程能够有效扩宽催化剂的光响应范围，提高其对可见光的利用率，促进光生载流子的分离及转移，加快表面光催化反应动力学，从而显著提高光催化水分解的活性。结合多种现代表征手段与理论计算，阐明了结构与催化活性的关系，揭示了光催化体系中光生载流子的迁移和分离机制，深入探究光催化水分解的微观机理。此外，我们在g-C3N4基复合纳米材料、金属硫化物基复合纳米材料的制备及其光催化制氢性能方面也开展了研究并取得了一系列创新性成果。我们的工作为进一步开发新型具有可见光响应的高效稳定光催化材料，拓展其在能源转化和环境净化等相关领域的新应用提供了重要科学参考。项目执行期间发表相关研究成果SCI论文26篇，包括Chemical Engineering Journal，Applied Catalysis B: Environmental，Chinese Journal of Catalysis和ACS Sustainable Chemistry & Engineering等国内外权威期刊，2篇论文入选ESI前1%高被引论文，培养毕业研究生11名（博士生3名，硕士生8名）。