Titanium Dioxide Modified Multi-Walled Carbon Nanotubes as Room Temperature NH3 Gas Sensors

Plasma treated and atomic layer deposition (ALD) modified multi-walled carbon nanotubes (MWCNTs) were investigated for their gas sensing properties towards ammonia gas. Titanium dioxide was deposited by ALD on plasma treated nanotubes and these modified and pristine nanotubes were compared for their gas sensing behavior. Functionalized MWCNTs showed higher response as compared to untreated ones. This favored response was the result of the increase in the defect density after plasma treatment and TiO
2
coating by ALD. Defects act as active sites for adsorption of ammonia gas molecules enhancing the sensitivity. Increase in the defect density was also proved with Raman analysis. Morphology and microstructure of the modified MWCNTs were studied using SEM.