Ultra-sensitive room-temperature H2S sensor using Ag–In2O3 nanorod composites

Abstract

Ultra-sensitive H₂S sensors operated at room temperature were fabricated using Ag–In₂O₃ nanorod composites synthesized using sol–hydrothermal method followed by NaBH₄ reduction process. TEM proved that the In₂O₃ was nanorod structures of ~ 110 nm in length and ~ 35 nm in diameter. Ag nanoparticles with diameters from 10 to 15 nm homogeneously decorated on the surfaces of the In₂O₃ naonorods. XRD and XPS analysis proved that the Ag elements existed as zero-valent metallic silver on the surface of the In₂O₃ nanorods. Ag nanoparticles could enhance the formation of chemisorbed oxygen species and interactions between H₂S molecules and oxygen species due to spillover effect, and the electron transfer between Ag and In₂O₃ nanorods also enhanced the sensing properties. Therefore, the H₂S sensors based on the Ag–In₂O₃ nanorod composites showed significantly improved sensing performance than those based on the pure In₂O₃ nanorods. The optimized content of Ag nanoparticles is 13.6 wt%. Operated at room temperature, the H₂S sensors made of 13.6 wt% Ag–In₂O₃ nanorod composites exhibited an ultra-high response of 93719 to 20 ppm H₂S and a superior detection limit of 0.005 ppm. The sensor also showed good reversibility, good selectivity, excellent reproducibility and stability for detection of H₂S gas.