Smog-Eating Photocatalytic Coatings

News: Delhi government and IIT Madras began a six-month study on “smog-eating” photocatalytic coatings to test reduction of NO₂ and volatile organic compounds (VOC) pollutants.

About Smog-Eating Photocatalytic Coatings

• It is a coating using titanium dioxide that neutralizes harmful gases like nitrogen dioxide (NO2) and volatile organic compounds (VOCs).
• Mechanism
  • Photocatalytic activity uses light energy to break down harmful substances and organic waste into less toxic or harmless matter.
  • When exposed to sunlight, titanium dioxide acts as a catalyst and generates surface electrons.
  • These electrons react with pollutants such as nitrogen dioxide and volatile organic compounds and dismantle them.
  • This process helps in making air and water cleaner.
• Technology used: Titanium dioxide is used as it is low-cost, chemically stable and compatible with construction materials.
• Targeted pollutants: It targets nitrogen dioxide and volatile organic compounds and prevents secondary particulate matter and ground-level ozone formation.
• Applications: It is applied on roads, pavements, buildings, and tiles, where it works as a passive air-cleaning system.
• Limitation: Its efficiency reduces due to low sunlight, dust accumulation, and wind conditions, and it may cause nitrate runoff leading to eutrophication in water bodies like Yamuna.