“The damage that one N2O can do is 300 times higher than that of CO2,” said Yi Liu, WSU Voiland PhD candidate.

N2O is part of a class of chemicals referred to as “NOx” (s). These chemicals contain only N and O. They are very harmful to the environment.

N2O itself is the third most major greenhouse gas, and thus a major contributor to climate change.

One important source of N2O emissions is from cars.

 “All the cars have catalytic converters and what they didn’t realize when they applied the converters to the car is that it will increase N2O emissions,” said Liu.

The catalytic converter is what turns pollutants into less harmful gasses in a car.

“That’s why we want to add on some catalysts to remove the N2O formation during the process,” said Liu. 

The catalyst would decompose N2O into Nitrogen and oxygen. This is the focus of Liu’s research.

This would most likely be placed after the catalytic converter.

On the structure of the catalyst, “I’m using single atom,” said Liu.

Single atom catalysts (SACs) involve isolated metal atoms on a support. A support is a solid that holds the metal in place. In this case, the metal atom that is being isolated is rhodium and the support is Cerium Oxide (Ceria).

The major advantage of this is that it uses the rhodium more efficiently. 

“Rhodium is platinum group metal, it is very expensive, and we don’t want to waste a lot of money,” said Liu.

More efficient use of metals is a major focus of research in the catalysis area.

The major problem with SACs is stability. The metal atoms will move around during a reaction and clump together to form clusters. This is not found to be an issue with this catalyst.

Diving deeper into the catalyst structure,

 “Recently one of my work is to use a little bit of ruthenium to modify the surface and then it will activate the oxygen species,” said Liu.  

Activation is making something able to react. In this case, it allows for oxygen from the support to participate in the reaction.

The reaction follows a certain set of steps, often referred to as a mechanism by chemists.

“First the N2O will absorb to the catalyst,” said Liu. This occurs on the isolated rhodium atom.

In the next step, the Nitrogen oxygen bond is broken, and nitrogen gas is released. The oxygen is still attached to the rhodium.

The active oxygen formed by the ruthenium will then react with the oxygen from the N2O to form O2 gas.

This active oxygen is from the Cerium Oxide, thus there is a missing oxygen in the cerium oxide support.

The missing oxygen will be replaced by oxygen from a new N2O molecule. The new N2O molecule will attach at the rhodium, release nitrogen gas,and then the remaining oxygen will fill in the missing oxygen.

The catalyst is now ready to repeat the first step of the reaction.

Using this catalyst under normal pressures, 

“The reaction achieves one hundred percent conversion at temperatures lower than 300, (degrees Celsius),” said Liu.

One hundred percent conversion means there are effectively no N2O molecules left.