Enhanced Acetaldehyde Sensing Performance of Spherical Shaped Copper Doped ZnO Nanostructures

Spherical shape copper (Cu) doped ZnO nanostructures of various amount (3, 6, 9 and 12 %) were synthesized. The XRD, FTIR, UV-Visible, HR-TEM, FESEM, EDS, SAED and XPS were done to understand the structural, optical, morphology and shape of Cu doped ZnO nanostructures. To achieve the best gas reaction, doping concentration was optimized. ZnO and Cu doped ZnO nanostructures were exposed to various oxygenated volatile organic compounds (OVOCs) and found to be more selective towards acetaldehyde sensing. For 50 ppm acetaldehyde gas, temperature study was done at various temperatures (RT, 50, 100, 150, 200 degrees C) which showed optimal at 100 degrees C for maximal gas response. The response and recovery time was 16.53 and 18.36 seconds for 50 ppm of acetaldehyde gas. The gas sensing study was carried out at different humidity rates (11, 32, 51, 63 and 84 %) using different saturated solutions. 9 % Cu doped ZnO shows maximum response (61.53 %) as compared to pure ZnO and 3, 6 and 12 % Cu doped ZnO. The spherical shape Cu doped ZnO sensing response was increases with increase in concentration of gas from 10 to 300 ppm. Acetaldehyde gas shows enhanced selectivity towards spherical shape Cu doped ZnO sensors as compared to the other OVOCs like acetone, ethyl methyl ketone, methanol, ethanol, n-propanol, n-butanol, formaldehyde, acetaldehyde, propionaldehyde and acrolein. The reproducibility of Cu doped ZnO was studied for 50 days. Also, after acetaldehyde gas sensing change in morphology study of sensor was done.