Studies on gas sensing performance of pure and surface modified Ti0 2 thick film resistors

Thick films of AR grade Ti0 2 were prepared by standard screen- printing technique. The gas sensing performances of thick films were tested for various gases. It showed maximum sensitivity to H 2 S at 300 °C for 100 ppm. To improve the sensitivity and selectivity of the film towards a particular gas, Ti0 2 thick films were surface modified by dipping them in an aqueous solution of 0.01 M nickel acetate tetra hydrate for different intervals of time. These surface modified Ti0 2 film showed larger sensitivity to H 2 S gas (100 ppm) than pure Ti0 2 thick film at 300 °C. Nickel oxide on the surface of the films acts as a catalyst and it increases reactivity of the films to H 2 S gas. A systematic study of sensing performance of the sensor indicates the key role-played by nickel oxide on the surface. The sensitivity, selectivity, response and recovery time of the sensor were measured and presented.