P-Cuo/N-Tio2 Heterojunction Nanostructure-Based Surface Acoustic Wave Sensor with Strong Electric Loading Effect for Highly Sensitive H2s Gas Sensing

A surface acoustic wave (SAW) H2S gas sensors based on CuO-TiO2 p-n junction film was designed and fabricated. The film composed of p-type CuO and n-type TiO2 shows significant current response to H2S. Moreover, the work point of SAW sensor based on CuO-TiO2 composite film is in high sensitivity region. As a result, the sensor demonstrates high sensitivity to H2S because of the large negative frequency shift contributed by electric loading. Besides, the change of linearity for frequency shift is strongly associated with the location of work point with the increasing H2S concentration from 1 to 300 ppm. On the other hand, the porosity of CuO-TiO2 is beneficial to the efficient adsorption for H2S, leading to the higher frequency response of the sensor. The SAW sensor also exhibits good selectivity and stability to H2S, with stable frequency shift under different humidity levels.