Why can cerium oxide play such a significant role in the automotive field?

Cerium oxide plays a huge role in the automotive field mainly because it possesses unique physical and chemical properties.
In terms of chemical properties, cerium oxide is a rare earth oxide with excellent redox properties. In the treatment of automobile exhaust, it can serve as a key component of catalysts. Automobile exhaust contains harmful pollutants such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx). Cerium oxide can participate in redox reactions, promoting the oxidation of carbon monoxide and hydrocarbons, converting them into carbon dioxide (CO₂) and water (H₂O), and at the same time facilitating the reduction of nitrogen oxides to reduce harmful gas emissions. For example, in three-way catalysts (TWC), cerium oxide can store and release oxygen. When the engine operates under rich-burn conditions (the air-fuel ratio is less than the stoichiometric ratio), a large amount of carbon monoxide and hydrocarbons will be produced. At this time, cerium oxide can release the stored oxygen to help oxidize these pollutants; while under lean-burn conditions (the air-fuel ratio is greater than the stoichiometric ratio), cerium oxide can absorb the excess oxygen, thus keeping the catalyst in an efficient working state all the time and effectively purifying the exhaust gas.
In terms of physical properties, cerium oxide has high hardness and good wear resistance. In the polishing and grinding processes of automobiles, cerium oxide can be used as an abrasive. For example, in the polishing of automobile paint surfaces, polishing agents containing cerium oxide can remove tiny scratches and flaws on the paint surfaces, making the paint surfaces smoother and flatter. This is because cerium oxide particles can flatten the uneven parts of the paint surfaces through physical grinding action, and at the same time, due to its moderate hardness, it will not cause excessive damage to the paint surfaces.
In addition, cerium oxide can also be used in the ultraviolet-proof coatings of automobile glasses. It can absorb and reflect ultraviolet rays, reducing the harm of ultraviolet rays to passengers and interior decorations in the vehicle. Ultraviolet rays can cause the aging and fading of materials such as plastic parts and fabrics in the vehicle, and coatings containing cerium oxide can effectively block ultraviolet rays, prolong the service life of interior decoration materials, and also provide better sun protection for passengers. Cerium oxide is also applied in the ceramic coatings of automobile engine components. It can enhance the high-temperature resistance and corrosion resistance of the coatings, improving the service life and performance of engine components. For example, adding cerium oxide to the ceramic coatings on the surfaces of components such as pistons and valves can better resist the scouring and corrosion of high-temperature combustion gases, ensuring the stable operation of the engine.