Mesoporous SnO₂ Nanotubes via Electrospinning–Etching Route: Highly Sensitive and Selective Detection of H₂S Molecule

We report the facile synthesis of thin-walled SnO 2 nanotubes (NTs) with numerous clustered pores (pore radius 6.56 nm) and high surface area (125.63 m 2 /g) via selective etching of core (SiO 2 ) region in SiO 2 –SnO 2 composite nanofibers (NFs), in which SnO 2 phase preferentially occupies the shell while SiO 2 is concentrated in the center of the composite NFs. The SiO 2 -etched SnO 2 NTs are composed of ultrasmall crystallites (∼6 nm in size) originating from crystal growth inhibition by small SiO 2 domains, which are partially segregated in the polycrystalline SnO 2 shell during calcination. These features account for efficacious diffusion and innumerable active sites, which maximize interaction between background gas (air) and analyte gas (H 2 S). Evaluation of gas-sensing performance of the porous SnO 2 NTs before and after decorating the exterior and interior walls with Pt nanoparticles (NPs) reveals exceptional selectivity and superior response ( R a / R g ) of 154.8 and 89.3 to 5 and 1 ppm of H 2 S, respectively. Excellent gas-sensing characteristics are attributed to the porous topography, nanosized crystallites, high surface area, and the catalytic activity of Pt/PtO x NPs.