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

We report the facile synthesis of thin-walled SnO₂ nanotubes (NTs) with numerous clustered pores (pore radius 6.56 nm) and high surface area (125.63 m²/g) via selective etching of core (SiO₂) region in SiO₂-SnO₂ composite nanofibers (NFs), in which SnO₂ phase preferentially occupies the shell while SiO₂ is concentrated in the center of the composite NFs. The SiO₂-etched SnO₂ NTs are composed of ultrasmall crystallites (∼6 nm in size) originating from crystal growth inhibition by small SiO₂ domains, which are partially segregated in the polycrystalline SnO₂ shell during calcination. These features account for efficacious diffusion and innumerable active sites, which maximize interaction between background gas (air) and analyte gas (H₂S). Evaluation of gas-sensing performance of the porous SnO₂ 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 H₂S, 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.