复合能隙可调Au纳米团簇抑制半导体光腐蚀及其机制研究

The study on photocorrosion suppression of semiconductors is of significant importance from both fundamental and practical viewpoints. It helps to improve the utilization efficiency of photogenerated charges and develop highly efficient photocatalysts. In this project, some typical semiconductors (such as ZnO, CdS etc.) are used as the objects of study. Au nanoclusters are proposed to combine to these semiconductors and noble metals are used as cocatalyst. The energy gap of Au nanocluster will be regulated to match the energy band of semiconductor. By the driving of a suitable potential difference, the photogenerated electrons and holes of semiconductor will be transferred to photostable noble metal cocatalyst and Au nanocluster respectively. The aim is to achieve the suppression of photocorrosion, enhance the charge separation efficiency and thus improve the phtotocatalytic performances. On this basis, the regulation mechanism of the energy gap of Au nanocluster on the photogenerated charge transfer paths and the reaction behaviors will be further studied. Furthermore, to reveal the mechanisms of photocatalytic water splitting and anti-photocorrosion on the as-prepared photocatalysts, the effects of photocatalyst microstructure and electronic structure on catalytic performances will be analyzed. The present study is expected to develop a new method for photocorrosion suppression of semiconductors, and it will be also helpful for guiding the design and preparation of future highly efficient and stable photocatalysts.

半导体光腐蚀抑制研究对提高光生电荷利用效率、研发高效光催化剂具有重要的基础意义和实用价值。本课题拟以几种典型的光腐蚀半导体（ZnO、CdS等）为研究对象，复合Au纳米团簇和贵金属助催化剂，通过调节Au纳米团簇能级带隙，使之与半导体的能带进行匹配。在适宜电势差的驱动下，将半导体的光生电子和空穴分别转移到光稳定的贵金属助催化剂和Au纳米团簇上。实现从根本上抑制半导体光腐蚀，并促进电荷分离，提高光催化性能。深入研究Au纳米团簇能级带隙对复合催化剂光生电荷转移路径和反应行为的影响机制。研究催化剂微结构和电子结构与催化性能之间的关系，揭示催化剂用于光催化分解水的反应机理和抗光腐蚀机理。通过本项目的研究，有望发展一种新的光腐蚀抑制方法，并为高效光稳定催化剂的设计和开发提供指导。

金属纳米团簇，特别是巯基保护的金纳米团簇，可通过液相合成法原子精准地制备，是近年来发展起来的一类新型超小（∼1 nm）纳米材料。因其尺寸接近于布拉格波长，能级发生离散表现出类半导体的光电特性，在光电催化中具有巨大的应用潜力。本课题组通过调节金纳米团簇的配体和尺寸，选控合成了能带结构和CdS匹配的谷胱甘肽保护的金纳米团簇。将其与易光腐蚀半导体CdS复合后同时提高了CdS的光催化活性和光稳定性。通过研究催化剂的组成结构、能带结构和光生电荷动力学发现，复合后金纳米团簇上的光生电子注入到CdS的导带，再迁移至助催化剂Pt；CdS的光生空穴迁移到金纳米团簇的HOMO。这样反向的电荷迁移既提高光生的电荷分离效率，又延长了光生电荷的寿命、同时抑制了空穴氧化CdS所致的光腐蚀。活性中间体追踪测试表明，复合金团簇之后自由基成为主要活性中间体，一定程度上减弱了空穴的光腐蚀。此外，本课题组还开发了一种通过配体嫁接过渡金属离子为金纳米团簇构筑催化位点的方法，首次实现了将金纳米团簇用于光催化反应，并结合第一性原理计算揭示了催化位点的作用机制。本项目的研究为金纳米团簇的功能化应用提供了两种策略，并从实验和理论上揭示了他们的作用机制，这些研究工作可为金纳米团簇基催化材料的开发和应用提供一定的指导和借鉴。