Photocatalytic NOx Removal

NOx + O2 + H2O → HNO3

Overview

TiO₂ photocatalyst on building surfaces oxidizes nitrogen oxides (NOx) from vehicle exhaust to nitric acid (HNO₃), which is then washed away by rain. Photocatalytic concrete and pavement coatings can reduce local NOx levels by 25–45%. This passive pollution remediation works continuously in sunlight.

Participants

Role Substance Coefficient State
Reactant Water H₂O 1 (l)
Product Nitric Acid HNO₃ 1 (aq)

Everyday Example

Some cities use photocatalytic concrete in roads and buildings that actively clean the air of vehicle exhaust pollution.

Industrial Importance

Photocatalytic construction materials represent a growing market for air quality improvement in urban environments.

Properties

Type
Photochemical
Reversible
No
Energy
Exothermic
ΔH
-206.0 kJ/mol
Catalyst
TiO₂ (titanium dioxide)

Related Reactions

Chlorophyll Fluorescence Cis-Trans Isomerization of Retinal Dye-Sensitized Solar Cell (Grätzel Cell) Firefly Bioluminescence (Luciferin Oxidation) Luminol Chemiluminescence Ozone Decomposition by UV Ozone Formation by UV Light Photocatalytic Water Splitting (TiO₂) Photochemical Cycloaddition ([2+2]) Photochemical Smog Formation (NO₂ Photolysis)

Frequently Asked Questions

What is the equation for Photocatalytic NOx Removal?
The balanced equation is: NOₓ + O₂ + H₂O → HNO₃.
What type of reaction is Photocatalytic NOx Removal?
Photocatalytic NOx Removal is a photochemical reaction.
Is Photocatalytic NOx Removal exothermic or endothermic?
Photocatalytic NOx Removal is exothermic (releases energy). The enthalpy change (ΔH) is -206.0 kJ/mol.
What conditions are needed for Photocatalytic NOx Removal?
This reaction requires a catalyst (TiO₂ (titanium dioxide)).