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 God's 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.