What is photocatalysis?
Photocatalysis is a process in which titanium dioxide (TiO2) in concrete, coating, or tiles uses UV light to accelerate a chemical reaction that breaks down dirt and air pollution on the surface. This creates a surface that is both self-cleaning and air-purifying.
How it works
Titanium dioxide is a photocatalyst: it is not consumed itself but speeds up the reaction. When UV light (from sunlight) strikes the surface, highly reactive particles are formed. These particles:
- break down organic dirt, soot, and algae;
- convert harmful nitrogen oxides (NOx) from exhaust fumes into harmless, washable compounds.
Because the surface also becomes hydrophilic (water-attracting), rainwater easily rinses away the broken-down dirt particles.
Properties
| Property | Effect |
|---|---|
| Self-cleaning | Facades and surfaces stay clean longer |
| Air-purifying | Breaking down NOx improves air quality |
| Low maintenance | Less cleaning and better appearance retention |
The effect depends on sufficient UV light; in shade or indoors it is limited.
Use in construction
Photocatalytic TiO2 is added to or applied on:
- facade panels and exposed concrete;
- paving and paving stones;
- roof tiles and facade paint.
Especially in urban areas with heavy traffic, it helps keep facades cleaner and improves air quality.
Related terms
- Exposed concrete
- Coating
- Facade paint
- Sustainable building
- Water repellent
- Roof tile
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