Nanomaterials play a key role in improving catalytic performance such as activity and selectivity for diverse energy applications. Typically, nanocatalysts are distributed on the surface of oxide support using wet chemical impregnation or physical/chemical depositions to achieve large active sites. Catalysts prepared by these top-down methods have stability limitations due to insufficient uniformity and poor adhesion between catalyst and support.
Exsolution, which is a phase separation phenomenon, can be an alternative nanotechnology for uniformly decorating robust nanoparticles due to its unique properties. In general, the targeted (catalytically active) metals are substituted as cations in a host oxide lattice during heat treatment or synthesis. Then, they are exsolved as nanoparticles from the oxide solid solution during a one-step reduction process at elevated temperatures. The grown nanoparticles are strongly socketed/embedded on the surface, leading to excellent resistance to carbon or sulfur poisoning and catalyst agglomeration.
Our group is dedicated to investigating the mechanism of exsolution phenomenon, encompassing the sequential processes of nucleation, socketing, growth, and shape shifting, to precisely control the composition, size, dispersion, and shape of the nanoparticles. In this way, we are finding new materials and novel strategies to control and promote exsolution behaviors. The advanced exsolution catalysts play a key role in facilitating thermochemical and electrochemical reactions in solid oxide cells, dry reforming, ammonia decomposition, and gas sensing.
Nanocomposite
Nanocomposite electrodes have attracted considerable attention as innovative solutions for maximizing the density of triple-phase boundaries (TPBs) and facilitating efficient ionic conduction pathways, thereby exhibiting high performance at intermediate temperatures (500–700 °C). Most nanocomposites have been used as air electrodes in fuel electrode- and electrolyte-supported cells because of their relatively low sintering temperatures (700–900 °C). Our group is engaged in developing new nanocomposite electrode configurations that extend their application beyond air electrodes and fuel cells.
