A comparative study on ethanol gas sensing properties of ZnO and Zn0.94Cd0.06O nanoparticles

• Synthesis of ZnO and Zn0.94Cd0.06O nanoparticles with particle size of 20–25 nm.
• Fabrication of a tubular ethanol sensor based on ZnO and Zn0.94Cd0.06O nanoparticles.
• ZnO and Zn0.94Cd0.06O -based sensors with fast response time of 100–200 s.
• ZnO and Zn0.94Cd0.06O -based sensors with optimum operating temperature of 250 °C.
• Improved gas sensing properties of the nanoparticles compared to ZnO microparticles.

Nanocrystalline ZnO and Zn0.94Cd0.06O particles were synthesized using sol–gel method and were characterized for their structural and morphological properties by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDXS). The results confirmed the formation of pure and spherical ZnO and Zn0.94Cd0.06O nanoparticles with wurtzite crystal phase and particle size of 20–25 nm obtained by TEM. Additionally, the ethanol sensing properties of ZnO and Zn0.94Cd0.06O based sensors were investigated for different operating temperatures/concentrations and they were compared with commercial ZnO microparticles. Comparative results demonstrated that Zn0.94Cd0.06O nanoparticles exhibit higher and faster response to 250 ppm of ethanol at 250 °C. Results on response/recovery time, sensing mechanism, conductance variation and thermodynamic/kinetic investigation of ethanol sensing mechanism is also studied and discussed.