Influence of Cu doping on the structural, photoluminescence and formaldehyde sensing properties of SnO2 nanoparticles

In this paper we report Cu doping induced modifications in the structural, photoluminescence and gas sensing behaviour of SnO2 nanoparticles. Our results show that crystallinity is reduced upon Cu doping. The PL emissions observed in the visible region are attributed to the defect levels arising due to oxygen vacancies. The 1.5 at% Cu-doped SnO2 shows the selective high response (similar to 80%) to 50 ppm concentration of formaldehyde over methanol, ethanol, propanol-2-ol, acetone and n-butylacetate at 200 degrees C. The sensing mechanism has been explained based on chemisorption of oxygen on the SnO2 surface and the subsequent reaction between the adsorbed oxygen species and the formaldehyde molecules.