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Research

Nanocatalyst

Exsolution

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

Nanocomposites play a critical role in improving the electrochemical performance of solid oxide cells (SOCs) by offering higher ionic conductivity and catalytic activity. Conventional Ni-based cermet electrodes exhibit insufficient ionic conductivity and sluggish surface kinetics at lower temperatures.

Nanocomposites provide a promising alternative by embedding uniformly dispersed nanoparticles onto a core structure. In Ni/YSZ-YSZ composites, Ni and YSZ nanoparticles are deposited onto a YSZ core, creating a large surface area for reactions and improving ionic pathways. These materials are synthesized using methods such as Pechini-type polymerization, which ensures strong particle connections and prevents agglomeration during high-temperature sintering. The main advantage of nanocomposites is their ability to enhance fuel oxidation while addressing issues like Ni coarsening and carbon deposition, resulting in improved durability, stable performance, and higher efficiency at intermediate temperatures.

In addition to Ni/YSZ-YSZ, other compositions are being explored. NiFe/YSZ-YSZ is fabricated for high-performance CO₂ electrolysis, and Ni/BZCY-GDC improves interface bonding, further maximizing stability in protonic ceramic fuel cells (PCFCs). Nanocomposites are crucial for advancing SOCs and related technologies, offering improved performance, durability, and adaptability across various energy systems.