Fang Song

Fabrication and good ethanol sensing of biomorphic SnO2 with architecture hierarchy of butterfly wings

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 degrees C).

3D hierarchical porous SnO2 derived from self-assembled biological systems for superior gas sensing application,

Mother Nature has always taught us lots about the arcanum of Gods creation, which primarily ties to the wonderful and complex self-assembly of biomolecules even in a mild condition. In the present work, we put forward a bio-inspired strategy, that is, directly bring in biological systems capable of self-assembly to fabricate functionalized hierarchical structures for effective gas sensing. For advanced pollination, biomolecules in pollen coats could self assemble to form bio-structures with effective mass transportablity, and herein were used to guide the self assembly of SnO2-precusors, which finally transferred to SnO2 materials by calcination. Gaining the 3D hierarchical porous structrues formed in the self-assembly of biomolecules, the as-fabricated SnO2 has high connective porous networks from macro- to micro-, and even nanoscale. The specific structures could facilite target gases to quickly transport towards, and then fully react with, the SnO2 nanoparticles, and thus endow the SnO2 with excellent gas response to both reducing gases (C2H5OH and CH3CH2CH3) and oxidising gas (Cl2). This present strategy provides a novel and facile way towards the development of functionallized hierarchical structures by learning from natural self-assembled systems. The resultant hierarchical structures can be extended to other applications in filters, adsorbents, catalysis, thermal, acoustic and electrical insulators, and so on.

Bioinspired Au/TiO2 photocatalyst derived from butterfly wing (Papilio Paris)

The reticular hierarchical structure of butterfly wings (Papilio Paris) is introduced as template for Au/TiO(2) photocatalyst by depositing the Au nanoparticles on TiO(2) matrix, which is carried out by a water-ethanol sol-gel procedure combined with subsequent calcination. The obtained Au/TiO(2) nanocomposites present the reticular hierarchical structure of butterfly wings, and Au nanoparticles with an average size of 7 nm are homogeneously dispersed in TiO(2) substrate. Benefiting from such unique reticular hierarchical structure and composition, the biomorphic Au/TiO(2) exhibits high-harvesting capability and presents superior photocatalytic activity. Especially, the biomorphic Au/TiO(2) at the nominal content of gold to titanium of 8 wt% shows the highest photocatalytic activity and can completely decompose methyl orange within 80 min, which is obviously higher than that of commercial Degussa P25 powders.

Bioinspired ultraviolet reflective photonic structures derived from butterfly wings (Euploea)

Butterfly wings have been demonstrated to have potential applications in various optical devices. For complementarily, we extend them to ultraviolet (UV) reflectors, inspired by the UV reflective photonic structures that have been evolved to satisfy UV communication systems of butterflies. UV reflective photonic structures of butterfly wings were replicated in multiscale, and thus endowed the resultant SnO2 materials with enhanced UV reflection. This biomimetic strategy provides us a universal way towards UV reflectors without changing the chemical compositions. Furthermore, the UV reflection could be potentially tuned by choosing different photonic structures of butterfly wings and other bio-species.

Controllable reflection properties of nanocomposite photonic crystals constructed by semiconductor nanocrystallites and natural periodic bio-matrices

In this contribution, the subtle periodic nanostructures in butterfly wings and peacock feathers are applied as natural PhC matrices to in situ embed CdS nanocrystallites (nano-CdS) on the structure surface via a convenient solution process. The resulting nano-CdS/natural PhCs nanocomposites show typical 1D, quasi 1D and 2D PhC structures at the nanoscale, which is inherited from the corresponding natural periodic bio-matrices. Moreover, their reflection properties are investigated and show dependence on PhC type, structure parameter, loading amount, as well as collecting angle. This work suggests that natural periodic bio-structures could be perfect matrices to construct novel nanocomposite PhCs, whose photonic band structures are tunable and thus achieve controllable optical properties. Related ideas could inspire the design and synthesis of future nanocomposite PhCs.