Ultra-Small Noble Metal Ceria-Based Catalytic Materials: From Synthesis to Application

At present, catalysts play an important role in modern industries, and there are 80 percent of industrial reactions need the participation of catalysts. Noble metal catalysts have significant applications in many fields because of the high selectivity, fine stability and excellent reactivity. However, the large-scale applications of noble metal are limited by the high price. Preparing noble metal catalysts as small as possible or even in single atom dispersion, can effectively improve the atomic, which partly solves the problem of high price. Nevertheless, this will lead to another problem that the surface free energy increases quickly when the size of noble metal decreases, resulting in the aggregation of noble metal. To address this issue, a suitable support is needed to fix noble metal. CeO2, as an ideal supporting material, has received widespread attention due to the excellent properties including two valences which are easy to interconvert, high oxygen storage capacity and a large number of oxygen deficiencies. So far, the ultra-small noble metal ceria-based catalytic materials have been widely developed in many catalysis fields, such as CO oxidation, water-gas shift reactions, hydrogenation reaction, etc. In this review, the controlled preparations, influence factors and applications of ultra-small noble metal supported on CeO2 carrier are introduced. Besides, the developments and challenges of this field are proposed.