Room temperature chlorine gas sensing using surface modified ZnO thick film resistors

Thick films of pure and CuO-modified ZnO were prepared by screen-printing technique. Pure ZnO was observed to be almost insensitive to chlorine gas. Pure ZnO white powder was calcined at 1100 °C for 24 h, to minimize the oxygen deficiency. CuO-modified ZnO thick films were obtained by dipping technique in which Cu2+ could be incorporated as an additive into the ZnO base material. The films were fired at 500 °C for 24 h. The CuO-modified sensor was observed to be sensitive to 300 ppm Cl2 gas at room temperature. The effect of operating temperature, calcination temperature, gas concentration, amount of CuO in ZnO on the gas response was studied. The selectivity of the target gas against other gases, gas response and recovery times of the sensor were also presented. The quick response (∼18 s) and fast recovery (∼50 s) are the main features of the modified sensor.