Facile Au catalyst loading on the inner shell of hollow SnO2 spheres using Au-decorated block copolymer sphere templates and their selective H2S sensing characteristics.

Hollow SnO2 spheres functionalized by Au catalysts were synthesized via the use of Au-decorated block copolymer (Au-BCP) sphere templates. Uniformly distributed Au nanoparticles on BCP spheres were prepared by the infiltration of Au precursors into polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) spheres. A thin SnO2 layer was coated on the Au-BCP spheres using RF sputtering at room temperature without morphological deformation of the spheres. The Au nanoparticles were uniformly transferred from the Au-BCP spheres to the inner shells of the hollow SnO2 spheres followed by decomposition of BCP spheres. The Au-loaded hollow SnO2 spheres exhibited a superior H2S sensitivity (Rair/Rgas = 17.4 at 5 ppm) with remarkably selective characteristics with a minor response (Rair/Rgas < 2.5 at 5 ppm) toward other interfering gases. Our results pave the way for a new catalyst loading method using Au-BCP spheres for the uniformly distributed Au NPs on the SnO2 layers.