Fast response and selective sensing of hydrogen sulfide by Ag nanoparticles modified MoO3 composites

Noble metal modifications can promote surface interactions between target vapors and metal oxides. The surface effect plays a significant role in influencing the gas response of materials. The size range of Ag nanoparticles is about 20–30 nm, which are uniformly modified on the surface of α-MoO 3 . This was achieved through a chemical reduction method, where sodium borohydride served as the reducing agent and L-lysine was utilized as a stabilizer for the nanoparticles. The uniform coating of Ag nanoparticles on the α-MoO 3 is expected to enhance the gas-sensing properties of the composite material. The α-MoO 3 sensor based on 10 mol% AgNPs modification showed the highest response at 200 ℃, which was 1.6 and 1.66 times greater than the response of the pristine α-MoO 3 sensor when tested at concentrations of 5 and 10 ppm, respectively. For H 2 S levels of 10, 20, and 40 ppm, the times for response and recovery were merely 9/20 s, 7/24 s, and 9/25 s, respectively, showing fast response recovery characteristics. The enhancement of the gas-sensitive sensing mechanism for hydrogen sulfide can be explained in terms of the electronic sensitization and chemical sensitization of α-MoO 3 .