Nano cerium oxide is an important member of rare-earth compounds. This light yellow to pale-yellow powder has a high density of 7.13 g/cm³ and an impressive melting point of 2397°C. Although it is insoluble in water and alkalis and only slightly soluble in acids, it exhibits outstanding polishing performance. Its versatile properties enable it to serve not only as a polishing material, but also as an efficient catalyst, catalyst support, and ultraviolet absorber. It also performs exceptionally well in applications such as fuel cell electrolytes, automotive exhaust treatment, and electronic ceramic materials.
Properties of Nano Cerium Oxide
Excellent Catalytic Performance
Oxygen Vacancies and Redox Activity: One of the most essential characteristics of nano cerium oxide is its ability to reversibly switch between Ce³⁺ and Ce⁴⁺ states while forming and eliminating oxygen vacancies within its crystal lattice. This enables it to efficiently store and release oxygen, making it an exceptional redox catalyst and catalyst promoter.
Strong Free Radical Scavenging Ability (Enzyme-Mimicking Activity)
Depending on the surface pH environment, nano cerium oxide can reversibly exhibit superoxide dismutase (SOD)-like and catalase (CAT)-like activities. In acidic environments, it scavenges hydroxyl radicals (·OH), while in neutral or alkaline conditions, it eliminates superoxide radicals (O₂·⁻). This property forms the basis of its applications in biomedicine.
High Chemical Reactivity and Adsorption Capacity
As particle size decreases, specific surface area increases, and the proportion of surface atoms becomes higher, significantly enhancing chemical reactivity. This allows more effective interaction with reactants, improving catalytic efficiency and strengthening adsorption capacity.
Excellent Ultraviolet Absorption
Nano cerium oxide strongly absorbs and scatters ultraviolet radiation—particularly UVA (320–400 nm)—while remaining transparent to visible light. This makes it an ideal inorganic UV-protective material.
Precision Mechanical Polishing Performance (CMP)
At the nanoscale, cerium oxide particles possess moderate hardness. During polishing, they engage in complex chemo-mechanical reactions with the workpiece surface, achieving damage-free polishing and high flatness. This makes them especially suitable for materials requiring extremely high surface precision.
High Stability and Durability
Cerium oxide exhibits excellent chemical and thermal stability, with strong resistance to high temperatures and corrosion. High purity (99.99%) ensures minimal impurities, preventing undesirable side reactions under extreme conditions and enhancing reliability and service life in demanding environments.
Three Major Advantages of Nano Cerium Oxide
1. The “Perfectly Balanced Gentle Power”
The hardness of a polishing material is critical: too hard and it scratches the surface; too soft and it cannot remove imperfections effectively. With a Mohs hardness of approximately 6–7—between glass (5.5) and silicon (7)—cerium oxide offers a balanced hardness that enables it to efficiently smooth surface irregularities without leaving permanent scratches. It works like fine sandpaper on wood: smoothing rough spots without damaging the overall structure.
2. Built-In “Cleaning Power” Through Chemical Versatility
The magic of cerium oxide lies not only in physical abrasion but also in its unique chemical properties. Cerium readily switches between +3 and +4 oxidation states, almost as if it possesses a “transforming” ability. During polishing, cerium oxide reacts chemically with atoms on the surface of glass or silicon wafers, oxidizing stubborn impurities into more easily removable compounds. This dual action—chemical dissolution combined with mechanical friction—greatly enhances polishing efficiency, much like using a cleaning agent to dissolve stains before wiping them away.
3. Nanoscale Precision Operation
Cerium oxide nanoparticles typically range from tens to hundreds of nanometers in size—about one-thousandth the diameter of a human hair. Such tiny particles can precisely address microscopic surface defects, filling gaps and smoothing protrusions to achieve nanometer-level flatness. It is like using a miniature carving tool to restore a delicate artifact at the microscopic scale.
The Microscopic “Collaborative Stage” Behind Polishing
When cerium oxide nanoparticles come into contact with the polishing surface, a precise “team operation” begins. Driven by the polishing slurry, the nanoparticles act like countless tiny grinding wheels, rolling and rubbing across the surface at high speed. Mechanical forces continuously remove microscopic protrusions.
At the same time, the chemical activity of cerium oxide is activated. Surface cerium atoms cooperate with oxygen in the air or components in the polishing slurry to oxidize surface atoms into a loose oxide layer. This oxide layer acts like a “fragile armor,” making it easier for mechanical forces to remove, thereby accelerating the polishing process.
Interestingly, oxygen vacancies within cerium oxide can also adsorb debris generated during polishing, preventing secondary scratches. It functions like a built-in “vacuum cleaner,” polishing and cleaning simultaneously to maintain efficiency and surface integrity.
What's the Applications of Nano Cerium Oxide?
Based on these characteristics, cerium oxide with particle sizes of 10–200 nm and 99.99% purity plays an irreplaceable role in multiple high-tech fields:
1. Catalysis and Environmental Protection
Automotive Exhaust Purification: As a key promoter in three-way catalysts (TWC), it dynamically regulates the air–fuel ratio through oxygen storage and release, efficiently removing CO, HC, and NOx.
Industrial Emission Control: Used in diesel particulate filter (DPF) catalytic combustion and selective catalytic reduction (SCR) systems for flue gas denitrification.
Fuel Cells: Serves as an electrolyte material or composite anode material in solid oxide fuel cells (SOFC), enhancing electrode reactions and improving performance.
Chemical Synthesis: Functions as an oxidation catalyst in selective organic oxidation reactions.
2. Precision Polishing (CMP)
Semiconductor Manufacturing: Essential for ultra-precision planarization of silicon wafers, integrated circuits, memory chips, and sapphire substrates—critical for chip yield and performance.
Optical Glass: Used for polishing LCD glass substrates, precision optical lenses, and photomasks to achieve high surface quality.
3. Cosmetics
High-End Sunscreens: Acts as an inorganic UV absorber, providing broad-spectrum protection—especially against UVA—with good skin feel and high safety compared to traditional organic sunscreens.
4. Functional Coatings and Materials
UV-Resistant Coatings: Incorporated into polymers, coatings, and textiles to enhance resistance to UV-induced aging.
Anti-Fog and Self-Cleaning Coatings: Leveraging photocatalytic activity for anti-fog glass and self-cleaning surfaces.
High-Temperature Protective Coatings: Used in thermal barrier coatings (TBCs) for aerospace turbine blades to improve sintering resistance and service life.
5. Energy and Storage
Photocatalysis: Applied in water splitting for hydrogen production and degradation of organic pollutants.
Lithium-Ion Batteries: Used as an electrolyte additive or electrode modifier to improve safety and cycle life.
From Screens to Chips: The “Nano Craftsman” Everywhere
Today, cerium oxide nanoparticles have quietly permeated everyday life. The ultra-high-definition clarity of smartphone screens and the crystal-clear transparency of camera lenses rely on its precision polishing capabilities. In semiconductor manufacturing, wafer flatness directly affects chip performance, and cerium oxide nanoparticles are key to achieving nanometer-level precision.
As industries such as renewable energy and precision optics continue to evolve, this remarkable nanomaterial will unlock even more advanced technologies—continuing to polish a clearer, more precise future for us all.