生物分子辅助多元硫化物/石墨烯纳米结构的原位构建及可见光催化制氢研究

Photocatalytic water splitting into H2 using solar energy is considered to be one of the most ideal approaches to address energy and environmental problems.The bottleneck for photocatalytic hydrogen production using solar energy towards practical applications is to develop visible-light-responsive photocatalysts that are higly efficient, stable, inexpensive and environmentally benign. The project will focus on the in-situ growth of multi-metal sulfide/graphene nanocomposites with visible-light response, high-efficiency and long-time by the the methods of one-pot hydrothermal, solvothermal, microwave, reverse microemulsion as well cation exchange technique in the presence of biomolecules including cysteine, L-cystine, L-methionine and glutathione (GSH) as the sulfur source，the complexing molecule and the reducing agent under mild conditions. The band gap position of the photocatalysts can be determined by combining UV-vis absorption spectra with Mott-Schottky analysis. The key fundamentals of photogenerated charge separation and transportion as well as the photocatalytic mechanism will be investigated by Time-resolved spectroscopy, in-situ characterization techniques, theoritical calculations and the photocatalytic reactions. The inherent relationship between the electronic structure, crystal structure and surface structure and light response range, photocatalytic efficiency and stability of multi-metal sulfide/graphene nanocomposites will be revealed, which is helpful for constructing a novel photocatalytic system with high efficiency, high stability and low cost.

利用太阳光催化分解水制氢是人类从根本上解决能源与环境问题最理想的途径之一，而制约其规模化实用的瓶颈在于高效、稳定、经济、环保的可见光催化剂和催化体系的研制。本项目以经济环保的生物分子（半胱氨酸、L-胱氨酸、L-蛋氨酸、谷胱甘肽）作硫源、络合剂及还原剂，在温和条件下采用一步水热、溶热、微乳及离子交换等液相合成技术原位生长可见光响应、高活性、长寿命的高质量多元硫化物/石墨烯的纳米结构光催化材料；将时间分辨光谱与理论计算和光催化制氢有机地结合起来，深入研究光致电荷分离、传输及与水分子的相互作用等核心科学问题，揭示催化剂的电子结构、晶体结构和表面结构与光响应范围、光催化效率及稳定性之间的内在本质联系，为构建高效、稳定、经济的新型可见光光催化体系提供理论依据。

探索高效、低廉、环保的光催化制氢技术是一项极具挑战性的研究课题。而开发与研制可见光响应、高效、经济、环保、稳定的光催化材料及光催化体系是当前利用太阳能分解水制氢的关键。过渡金属硫化物具有窄的带隙与合适的导带和价带位置，是一类具有潜在应用前景的可见光光催化剂材料。尽管多元硫化物可见光催化产氢在近些年取得迅猛的进展，但总体而言，光催化制氢的效率还有待进一步提高，尤其直接分解水制氢的效率还很低，远未达到实际应用的要求。值得思考的是，为什么许多硫化物在可见光区具有很强的光响应，但其光分解水制氢活性很低，这主要与光催化反应中电子-空穴的分离和复合这两过程的竞争有关。如何促进光生电子和空穴的有效分离、抑制其快速复合，是光催化反应中极其关键的问题。我们以经济环保的生物分子作硫源、络合剂及还原剂，并以能带理论为基础，将异质结和固溶体技术作为能带结构调控手段应用于光催化剂设计，利用原位纳米组装技术构建并制备了Mn-Cd-S、Zn-Cd-S、Mn-In-S固溶体以及Ag2S-CdS、NiS/Nb6-CdS、NiS/P5W106-CdS、ZnIn2S4-In(OH)3等异质结硫化物高效光催化体系，在可见光照射、且无任何助催化剂时，部分光催化制氢量子产率最高可达73.8%。利用先进的谱学技术、光电化学手段对光催化过程中电子-空穴的分离与传输以及光催化制氢的原理等关键科学问题进行研究，为研制和组装新型高效光催化复合体系提供了可行的思路。