Methane is a bad greenhouse gas. It traps a lot of heat. Factories use catalysts with metal oxides to turn methane into less harmful gases. Ceria is a key part of this process because it can store and release oxygen. But how oxygen moves inside ceria was not well understood.

A new study shows that ceria nanoparticles can switch between two ways of moving oxygen, depending on their size.

Ceria works by using its own oxygen to change other molecules, then it fills the empty space. It can get new oxygen from the air or from inside itself. Previous studies did not separate these two ways of getting oxygen.

The researchers made special catalysts with ceria particles of different sizes. They used platinum to help the reaction, but only in small amounts so it would not affect the results.

The team tested the catalysts using special experiments to see how they worked.

The experiments showed that small and large ceria particles worked differently. Small particles were better at capturing oxygen from the air when there was a lot of oxygen. Large particles were better at using their internal oxygen when there was not much oxygen.

The researchers found that the difference was due to the structure of the particles. Small particles had more surface area to capture oxygen, while large particles had more internal oxygen to use.

The researchers said this study is important because it shows how oxygen works in catalysts for the first time.

The researchers used their findings to improve the process of turning methane into less harmful gases. They found that small ceria particles worked better under certain conditions.

The small particles worked well even when it was humid, which is important for industrial applications.

The study shows that how well a catalyst works depends on how well oxygen can move through the material.

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Source: Korea Advanced Institute of Science and Technology (KAIST)