Surface cupricated SnO2–ZnO thick films as a H2S gas sensor

SnO2 (95 wt.%)–ZnO(5 wt.%) thick films have been prepared by screen printing and firing process. Sensitivity of these films to H2S gas was examined. These films are found better sensitive to H2S gas than pure SnO2 films. It may be due to porosity created by ZnO into SnO2 matrix. SnO2–ZnO film operates at 250 °C while pure SnO2 at 350 °C to have a maximum sensitivity. SnO2–ZnO thick films were surface cupricated to give extremely high sensitivity, fast response and recovery to H2S gas. In cuprication process, SnO2–ZnO films were dipped into aqueous solution of cupric chloride for different intervals of time and then sintered. A systematic evaluation of CuO species by SEM and EDAX indicates its crucial role in dictating both sensitivity and selectivity. The response and recovery time of SnO2–ZnO–CuO sensor have also been found to be significantly improved in comparison with SnO2–ZnO or CuO doped SnO2 sensors.