Highly sensitive Co3O4 nanoparticles/MEMS NO2 gas sensor with the adsorption of the Au nanoparticles

Abstract This study produces Co3O4 nanoparticles (NPs) using ultrasonic wave grinding technology. The experimental results show that the average diameter of Co3O4-NPs is about 6 nm. Au nanoparticles are adsorbed onto the surface of Co3O4-NPs and integrated with a MEMS structure to form a Au/Co3O4-NPs/MEMS NO2 gas sensor. The diameter of Au nanoparticle is approximately 1 nm. For a 100-ppb NO2 gas concentration, an Au/Co3O4-NPs/MEMS gas sensor has the greatest sensor response and has a higher sensitivity to NO2 than other gases (SO2, NH3, CO, CO2) when NO2 gas is introduced at 10 ppm and at the optimal operating temperature of 136 ℃.