Ag/MxOy光催化剂：基于稳定性银原子与银离子共混超小团簇(Agnδ+,2 ≤ n ≤ 4)的设计

Most recently, atomically dispersed catalysts have attracted rapidly increasing attention, especially for noble metals, due to their unique catalytic properties and highest atom efficiency. However, this research also faces the challenges from (1) Aggregation of single metal atoms (SMA) in liquid phase or through sintering,resulting from large special surface area of SMA. (2) Possibly, being against to concerted catalysis of ultiple atoms. So herein we suggest an improved method based on ultrafine cluster consisted of Ag(0) and Ag(I) (Agnδ+,2 ≤ n ≤ 4), which shows advantages as follows: (1)The positive charge of ultrafine cluster can protect their aggregation effectively. (2)This ultrafine cluster is closed to SMA in size, called quasi SMA. (3) There is a high possibility to carry out the concerted catalysis of multiple atoms. Our research project including: The ultrafine clusters (Agnδ+,2 ≤ n ≤ 4) will be prepared by both template and controllable reduction reaction, and then obtained products as precursor will be loaded on the surface of transitional metal oxides(MxOy), carrying out further investigations including second reduction reaction for generation of Ag(0) ultrafine cluster, photocatalysis and theoretical simulation. In addition, it should be concerned that the surface plasmon resonance (SPR) from independent, aggregation or self-assembly of Ag(0) ultrafine cluster, which might result in change of strength and position of light absorption.

近期，金属单原子催化剂已成研究热点，但尚待深入：（1）此类催化剂表面能巨大，液相中或高温时易团聚；（2）可能不适合多原子协同反应的催化。该申请项目拟开展基于银原子与银离子(Agnδ+,2 ≤ n ≤ 4)共混超小团簇的研究，特点：（1）该团簇自身带有电荷，通过团簇间静电排斥可有效防止团聚，有利于本项目后续研究；（2）相关的超小团簇，在尺度上仍接近单个原子（可称为准单原子），催化效率仍很高；（3）相关的超小团簇有可能实施多原子协同反应的催化。研究内容主要包括：首先采用模板加控制性还原的方法制备关键性产物(Agnδ+,2 ≤ n ≤ 4)；继而研究它与过渡金属氧化物（MxOy）的负载问题，包括二次还原成电中性原子簇(Agn,2 ≤ n ≤ 4)，光催化活性及理论计算，同时关注Ag超小团簇的孤立、聚集、自组装等状态下表面等离子效应（SPR）的强弱、光吸收位置等问题。

银基光催化剂因其良好的光响应性质和简便的合成方法而受到广泛研究，然而，银基光催化剂的光稳定性差强人意。本论文围绕银基复合催化剂的设计及光催化性能研究，侧重对银基光催化剂进行光化学响应和光生载流子的迁移机制调控，进而构建具有高效可见光响应且光稳定性优异的银基复合光催化剂。.研究工作主要包括：.1. Ag/MxOy型光催化剂的设计、制备探索，力求实现基于Ag超小团簇的复合结构。.2. 高效银系纳米晶与C3N4，C3N5复合光催化体系的构建；.3．高效银系纳米晶与改性黑云母复合光催化体系的构建；.4. 本项目在开展高效银系光催化剂研究的同时，还支撑了Bi2WO6等其他光催化体系的研究。.本项目采用多种表征手段对所合成光催化剂的晶相结构、微纳米结构、化学组成、比表面积、光化学性质、电化学性质、光催化性能以及光催化机理进行了系统的研究。上述高分散的负载型结构对于复合材料光催化活性的提高具有重要意义，与单一组分相比，这些复合材料表现出更好的光催化活性，其表观速率常数分别是单一组分的数倍至数十倍。