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) H 2 S gas sensor based on CuO-TiO 2 p-n heterojunction film was designed and fabricated. The sensor exhibits high sensitivity to H 2 S due to the significant current response of CuO-TiO 2 film to H 2 S gas and the appropriate work point of SAW sensor based on CuO-TiO 2 composite film. The linearity change for sensor frequency shift is strongly associated with the location of work point when the H 2 S concentration increases from 1 to 300 ppm. In addition, the porosity of CuO-TiO 2 film is beneficial to the efficient adsorption for H 2 S, leading to the higher frequency shift of the sensor. The SAW sensor also shows good selectivity and stability to H 2 S with stable frequency shift under different humidity levels. • A H 2 S gas sensor is designed and fabricated using CuO-TiO 2 composite film. • The establishment of CuO-TiO 2 p-n junction significantly enhances the sensitivity of SAW sensor to H 2 S. • The linearity variation of frequency shift is closely related to the position of work point at different H 2 S concentrations. • The key sensing mechanism of SAW sensor based on CuO-TiO 2 film is electric loading. • The SAW sensor shows fast response in high humidity level, and good gas selectivity and repeatability. [ABSTRACT FROM AUTHOR]