High performance chemiresistive H2S sensors using Ag-loaded SnO2 yolk–shell nanostructures

Abstract

SnO₂ yolk–shell spheres uniformly loaded with Ag nanoparticles were prepared by a facile one-pot ultrasonic spray pyrolysis of the source solution and the H₂S sensing characteristics were investigated. The Ag-loaded SnO₂ yolk–shell spheres showed ultrahigh and reversible response (R_a/R_g − 1 = 613.9, where R_a is the resistance in air and R_g is the resistance in gas) to 5 ppm H₂S with negligible cross-responses (0.6–17.3) to eight other interference gases at 350 °C. In contrast, pure SnO₂ spheres with dense inner structures and yolk–shell morphologies did not exhibit a high response/selectivity to H₂S nor reversible H₂S sensing. The highly sensitive, selective, and reversible H₂S sensing characteristics were explained in terms of the gas-accessible yolk–shell morphology and uniform loading of catalytic Ag nanoparticles. Namely, the gas-accessible yolk–shell morphology facilitated the rapid and effective diffusion of the analyte/oxygen gases and the uniform loading of Ag nanoparticles promoted the H₂S sensing reaction.