High humidity enhanced surface acoustic wave (SAW) H2S sensors based on sol–gel CuO films.

• The sensor can detect H 2 S gas with a concentration as low as 0.5 ppm. • The frequency shift of sensor is derived from the change of mass loading on films. • The responses became much faster and stronger with the increase of RH. Surface acoustic wave (SAW) sensors based on sol–gel processed porous and nanoparticulate CuO films were explored for H 2 S detection operated at room temperature. The SAW sensor showed a negative frequency shift when exposed to H 2 S gas, due to the mass loading effect on the sensitive CuO film. It has a high sensitivity of H 2 S, a detection limit of 500 ppb and a good selectivity to H 2 S gas compared with H 2 , C 2 H 5 OH, acetone, NH 3 , CO, NO, NO 2 gases. Relative humidity (RH) was identified to have a critical influence on the sensing performance of the sensor. The responses became much faster and stronger with the increase of RH. The significant enhancement in the sensing performance is attributed to that the chemical reaction between H 2 S and CuO is hindered and the physical adsorption of CuO to H 2 S is enhanced. [ABSTRACT FROM AUTHOR]