Nano Ag-DopedIn2O3Thick Film: A Low-TemperatureH2SGas Sensor

Abstract

Thick films of AR grade In2O3were prepared by standard screen-printing technique. The gas sensing performances of thick films were tested for various gases. It showed maximum sensitivity to ethanol vapour at 350°C for 80 ppm concentration. To improve the sensitivity and selectivity of the film towards a particular gas, In2O3sensors were surface-modified by dipping them in a solution of 2% nanosilver for different intervals of time. Obtained results indicated that spherical nano-Ag grains are highly dispersed on the surface of In2O3sensor. The surface area of the nano-Ag/ In2O3sensor is several times larger than that of pure In2O3sensor. In comparison with pure In2O3sensor, all of the nano-Ag-doped sensors showed better sensing performance in respect of response, selectivity, and optimum operating temperature. The surface-modified (30 min) In2O3sensor showed larger sensitivity to H2S gas (10 ppm) at 100°C. Nano silver on the surface of the film shifts the reactivity of film from ethanol vapour to H2S gas. A systematic study of gas sensing performance of the sensor indicates the key role played by the nano silver species on the surface. The sensitivity, selectivity, response, and recovery time of the sensor were measured and presented.