新型碳包覆超薄单晶TiO2纳米带基光催化剂的构筑及其太阳能驱动光解水产氢性能研究

Solar-driven hydrogen production from water-splitting is well recognized as one of most promising ways for solving problems related to environment and the limited supply of fossil fuels. The key problem is the development of high performance photocatalysts that can effectively harvest sunlight and simultaneously drive the photoreaction with high quantum efficiency. TiO2 is one of the most promising photocatalysts. However, the photocatalytic efficiency of TiO2 for solar driven water-splitting is substantially limited by its large bandgap and lower quantum efficiency. In this proposal, we propose a new method to design high-efficient solar-driven carbon covered ultrathin single-crystalline TiO2 nanobelts-based photocatalysts. The central idea is utilization of the excellent properties of uniform carbon coating ultrathin TiO2 matrix for effectively promoting the photogenerated charge separation, combining with regulation of energy level structure by bandgap engineering to improve the utilization of visible light. We will adopt the small molecular ligand assisted hydrothermal method to prepare ultrathin single-crystalline H2Ti3O7 nanobelts with 2-5 nm thickness, which has the advantage of shortening volume diffusion path of photoinduced charge to the surface-reactive sites. On this basis, the novel carbon coating ultrathin TiO2 nanobelt-based photocatalysts will be designed and prepared using the small molecular ligand as carbon source combining with the bandgap engineering.The as-prepared photocatalysts will be charcterized by various analysis techniques, and the excitation, separation, transport and transfer of photo-induced charge pairs will be detailedly studied. The catalytic activities of these novel carbon coating ultrathin single-crystalline TiO2 nanobelt-based photocatalysts towards hydrogen production in solar-driven water splitting reaction and the relationship between the solar-driven performance and the structure of the catalysts, as well as the mechanism of hydrogen production from solar-driven water splitting will be investigated and elucidated. We anticipate the studies in this proposal will provide some new theoretical and technical basis for the designing and preparation of high-performance solar-driven photocatalytic materials.

光解水产氢是解决能源、环境等难题最为理想的方法之一，其关键是光催化剂。针对TiO2光催化剂禁带宽度大、量子产率低等不足，本项目基于“超薄基体”和“均匀异质结(碳均匀包覆)”协同促进光生电荷分离的理念，开展高效太阳能驱动光催化剂的设计和制备研究。拟采用前期研究中发明的小分子配体辅助低温水热法，合成超薄钛酸纳米带(2-5 nm)。在此基础上，以引入的小分子配体为碳源，结合能带工程方法，借助自掺杂、半导体复合等方式，协同调控能级结构，构筑新型碳包覆超薄单晶TiO2 纳米带基光催化剂。系统分析催化剂的组成、结构和性质，重点检测其光生载流子的产生、传输及转移情况；考察所制催化剂的太阳能驱动光解水产氢性能，解析光催化剂的结构、性质与性能之间的关系，并探究其催化机理。本项目的成功实施，不仅可望获得高效光催化材料，为研发新型光催化剂提供重要参考，还有望为推动光解水制氢，为缓解能源和环境危机做出重要贡献。

光解水产氢技术是解决能源、环境等难题最为理想的方法之一，其核心是发展高效光催化剂。针对半导体光催化材料量子产率低等不足，本项目基于“超薄基体结合暴露高能晶面”的理念，设计及制备出系列高效太阳能驱动光催化剂，并探讨了它们的结构-性能关系：.1. 采用碱热法，结合室温组装反应，制得了长达数百纳米、宽约15-20 nm、厚仅2-5 nm的超薄钛酸纳米带，并探明其形成遵循“溶解-再结晶”机理，为超薄基底高催化材料的设计奠定了基础；.2. 制备出厚度约2 nm、接近100%暴露{010}高活性晶面的TiO2纳米带，提出并证实了光生电荷3D区域分离新机制。该光催化剂在模拟太阳光照射下产氢速率达29.1 mmol/g/h，较目前纯TiO2紫外光照下最高产氢速率提高1.24倍，并实现了锐钛矿TiO2全分解水；制得了类石墨化碳包覆暴露 (010) 晶面TiO2纳米带，其太阳光驱动产氢速率高达42.0 mmol h-1g-1催化剂，在紫外区的表观量子效率均高于95%。研究结果表明，“超薄基体结合暴露高能晶面”是提高TiO2基光催化材料活性的有效策略；.3. 为进一步验证“超薄基体结合暴露高能晶面”可以有效抑制光生电荷复合，设计及制备出厚约厚约1.5-2 nm、暴露（001）高能晶面的CdS纳米带。当负载廉价金属镍作为助催化剂时，可见光（λ＞400 nm）产氢速率高达417.5 mmol/ h/g。. 本课题从材料设计方面入手，获得了3种具有良好光催化活性的光催化材料，掌握了构筑高效光催化材料的一般规律，提出了“超薄基体结合暴露高能晶面”的半导体光催化材料改性新策略。本项目的研究为半导体光催化技术的发展奠定了基础。