Surface cupricated SnO 2–ZnO thick films as a H 2S gas sensor

Abstract

SnO 2 (95 wt.%)–ZnO(5 wt.%) thick films have been prepared by screen printing and firing process. Sensitivity of these films to H 2S gas was examined. These films are found better sensitive to H 2S gas than pure SnO 2 films. It may be due to porosity created by ZnO into SnO 2 matrix. SnO 2–ZnO film operates at 250 °C while pure SnO 2 at 350 °C to have a maximum sensitivity. SnO 2–ZnO thick films were surface cupricated to give extremely high sensitivity, fast response and recovery to H 2S gas. In cuprication process, SnO 2–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 SnO 2–ZnO–CuO sensor have also been found to be significantly improved in comparison with SnO 2–ZnO or CuO doped SnO 2 sensors.