Fabrication and good ethanol sensing of biomorphic SnO 2 with architecture hierarchy of butterfly wings

Abstract

Using super-hydrophobic butterfly wings as templates, we developed an aqueous sol–gel soakage process assisted by ethanol-wetting and followed by calcination to fabricate well-organized porous hierarchical SnO 2 with connective hollow interiors and thin mesoporous walls. The exquisite hierarchical architecture of SnO 2 is faithfully replicated from the lightweight skeleton of butterfly wings at the level from nano- to macro-scales. On the basis of the self-assembly of SnO 2 nanocrystallites with diameter around 7.0 nm, the interconnected tubes (lamellas), the fastigiated hollow tubers (pillars) and the double-layered substrates further construct the biomorphic hierarchical architecture. Benefiting from the small grain size and the unique hierarchical architecture, the biomorphic SnO 2 as an ethanol sensor exhibits high sensitivity (49.8 to 50 ppm ethanol), and fast response/recovery time (11/31 s to 50 ppm ethanol) even at relatively low working temperature (170 °C).