Defect engineered Co-doped SnO₂ thin films for highly sensitive NH₃ detection: a combined DFT and experimental study

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Sensing

Background:

• Tin dioxide (SnO₂) is a promising semiconductor material for gas sensors.
• Developing highly sensitive and selective NH₃ sensors is crucial for environmental monitoring and industrial safety.

Purpose of the Study:

• To develop high-performance Co-doped SnO₂ nanocolloidal thin films for NH₃ detection.
• To investigate the role of defect engineering in enhancing sensor performance.

Main Methods:

• Sol-gel synthesis for nanocolloidal thin film fabrication.
• X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Photoluminescence (PL), and UV-Vis spectroscopy for material characterization.
• First-principles Density Functional Theory (DFT) calculations for theoretical insights.

Main Results:

• 2% Co-doped SnO₂ exhibited a reduced crystallite size (4.88 nm) and band gap narrowing.
• Doping increased surface oxygen vacancies (Ov and O_C) and introduced mid-gap 3d states.
• A 153.54% increase in conductivity upon NH₃ adsorption and a selectivity ratio of 31.0 (vs. H₂) were observed.
• Improved sensor reversibility due to a lower NH₃ desorption barrier.

Conclusions:

• Co-doping significantly enhances the sensitivity, selectivity, and reversibility of SnO₂-based NH₃ sensors.
• Defect engineering is key to optimizing gas surface interactions and electronic properties.
• The developed 2% Co-doped SnO₂ films are excellent candidates for advanced NH₃ detection applications.