Switching Photocatalytic NH₃ Oxidation Pathways from NO_x to N₂ via Synergistic Kineto-Thermodynamic Modulation on...

Area of Science:

• Materials Science
• Environmental Chemistry
• Catalysis

Background:

• Ammonia (NH3) is crucial but poses environmental risks due to emissions.
• Photocatalytic oxidation of NH3 over TiO2 is a potential air purification method.
• Current methods suffer from poor selectivity, producing toxic nitrogen oxides (NOx).

Purpose of the Study:

• To design a modified TiO2 photocatalyst for selective NH3 oxidation.
• To address the issue of poor selectivity and NOx byproduct formation.
• To provide a design principle for efficient photocatalytic nitrogen management.

Main Methods:

• Synergistic defect-dopant engineering of TiO2.
• Controlled nitrogen (N) doping and oxygen vacancy (OV) creation.
• Analysis of reaction mechanisms and product selectivity.

Main Results:

• N doping promotes N2 formation by stabilizing intermediates.
• Oxygen vacancies (OVs) promote overoxidation to NOx and nitrates/nitrites.
• Optimized N-doped TiO2 achieved 87% NH3 conversion with 80% N2 selectivity and minimal NOx (<5 ppm).

Conclusions:

• Defect-dopant engineering is key to optimizing NH3 oxidation kinetics and thermodynamics.
• The developed catalyst offers high selectivity and stability for air purification.
• This strategy provides a pathway for sustainable management of nitrogen compounds.