金属纳米颗粒修饰光催化剂表/界面的作用机理及反应动力学研究

项目名称： 金属纳米颗粒修饰光催化剂表/界面的作用机理及反应动力学研究

项目编号： No.21503257

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 有机化学

项目作者： 苏韧

作者单位： 中国科学院山西煤炭化学研究所

项目金额： 21万元

中文摘要： 由于人类对可持续能源，化工产品，及环境治理的需求不断增加，光催化技术在过去几十年里成为全世界的研究热点之一。但绝大部分光催化剂在可见光辐照下量子效率极低，限制了光催化技术的工业应用。金属纳米粒子助催化剂修饰光催化剂表面可以分离空穴-电子对并延长其寿命，提高光催化产氢，二氧化碳还原，及污水处理等过程的量子效率。表面科学研究表明金属纳米颗粒的物性及金属-半导体间的相互作用会影响光催化剂系统的电子结构，进而影响催化活性。但是，光催化反应条件下金属纳米颗粒的作用机制尚不明确，限制了高性能光催化剂的设计。 本项目拟在真实反应条件下，通过原位分子探针技术及电子顺磁共振技术研究物性参数可控的金属纳米颗粒-光催化剂系统中（1）金属纳米颗粒表面储存的自由电子的动力学过程；（2）光催化剂不同能级激发态电子二次激发及界面电荷转移现象；（3）金属纳米粒子对反应自由基及光催化选择性的影响。

中文关键词： 光催化反应；助催化剂；金属纳米粒子；原位分子探针；界面电荷转移

英文摘要： Photocatalysis have been extensively investigated world-widely in the past decades for sustainable energy production, organic synthesis, and environmental applications. However the quantum efficiencies of photocatalytic reactions under visible light radiation conditions still need to be geared up to meet the demand of industrial operations. Surface modification of photocatalysts by metal nanoparticles (NPs) as co-catalyst has been considered to be one the most successful approaches to improve photocatalytic performances via spatial separation of photo-excited charges. Various synthesis methods have been applied for the deposition of metal NPs on photocatalysts for H2 production, CO2 reduction, and water purification applications, and it has been recognised that the physical properties of metal NPs (i.e., metal identity, particle size, and microstructure) influence the performance drastically. Fundamental researches in surface science revealed that the properties of metal NPs and the interaction between semiconductor and metal NPs governed the electronic properties of metal-semiconductor systems, thus are essential in enhancing photocatalytic performances. However, due to the complexity of photocatalytic reactions, very few researches have been attempted to address the question of how and why the metal NPs influence the performance in photocatalytic reaction conditions, thus limiting rational design and synthesis of highly active photocatalysts. This project is aiming to gain better fundamental understanding of the semiconductor-metal NPs interaction in real photocatalytic reaction conditions. The kinetics of photoexcited e- that are trapped on metal NPs, the identity and possibility of re-excitation of e- at different energy levels and environments, and the impact of photo-induced radical species on selective photocatalytic reactions will be investigated. To realise this, well-defined photocatalyst-metal NPs systems with tuneable physical parameters synthesised by controllable techniques will be investigated using self-developed in-situ molecular probing techniques and electron paramagnetic resonance coupled with theoretical calculations.

英文关键词： Photocatalysis;cocatalyst (promoter);metal nanoparticles;in situ molecular probing;interfacial charge transfer