Bio-templated fabrication of hierarchically porous WO3 microspheres from lotus pollens for NO gas sensing at low temperatures

Abstract

Lotus pollens were used as templates to prepare WO₃ microspheres; the intriguing structural features of the pollens, e.g. hollow sphere with highly porous double shells, were perfectly inherited by the WO₃ microspheres. The hierarchically porous structure of the WO₃ microspheres was ideal for gas sensing. The WO₃ microsphere-based sensor exhibited a high sensitivity (S = 46.2) to 100 ppm NO gas with a pretty fast response and recovery speed (62 s/223 s) at 200 °C. Compared with NO sensors reported in the literature so far, the WO₃ microsphere-based sensor has among the highest sensitivity and fastest response/recovery.