Smog-Eating Photocatalytic Coatings
Why in News?
On March 23, 2026, authorities began applying these coatings to public infrastructure, including flyovers, building facades, and streetlights in North Delhi, to test their real-world efficacy.
Key Features
- Primary Compound: Titanium dioxide (TiO₂), low-cost, chemically stable, and compatible with concrete, asphalt, and tiles.
- Mechanism: Photocatalysis—under UV light from sunlight, TiO₂ generates reactive oxygen species that oxidize pollutants into harmless CO₂ and water.
- Target Pollutants: Nitrogen oxides (NOx, including NO₂), volatile organic compounds (VOCs), and some hydrocarbons contributing to smog.
How It Works?
- Coating applied to surfaces absorbs sunlight, activating TiO₂ as a catalyst.
- Pollutants contact the surface and get decomposed without consuming the catalyst.
- Proven in trials for gaseous depollution on construction materials.
Applications
- Urban infrastructure: Roads, pavements, buildings, bridges in high-pollution areas like Delhi.
- Potential scalability: Pilot studies planned for large-scale use if effective.
- Earlier mentions: Feasibility study announced by Delhi in late 2025.
Advantages
- Cost-effective and durable for widespread adoption.
- No energy input needed beyond sunlight; self-cleaning properties reduce maintenance.
- Environmentally safe with no harmful byproducts.
Limitations
- Effectiveness depends on sunlight exposure and pollutant contact with surfaces.
- Questions on real-world efficacy in high-smog scenarios like Delhi winters.
- Initial studies ongoing to validate long-term impact.
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