Preparation of WO₃ nanoplatelet-based microspheres and their NO₂ gas-sensing properties

Abstract

Microspheres consisting of WO 3 nanoplatelets were prepared by a simple polyol process using tungsten chloride, poly-(vinylpyrrolidone) (PVP), and ethylene glycol. The microsphere sizes could be easily controlled by the appropriate adjustment of the molecular weight of the added PVP from 3500 to 1300000. The microspheres prepared by using PVP with a molecular weight of 1300000 had average diameters of about 877 nm and consisted of nanoplatelets that were ³500 nm long by 30 nm wide. The gas-sensing properties of the WO 3 microspheres were investigated by exposure to 50 ppb to 1 ppm NO 2 . The sensor element constructed with microspheres composed of the PVP with a molecular weight of 1300000 showed a higher sensor response to NO 2 gas than the others, because the nanoplatelets had smaller particle sizes and larger specific surface areas.

Photochromic properties of novel composites on the base of biopolymers and plasma‐modified Mo4O11 and W18O49 nanostructures

“…The size of the resulting structures can be varied using organic stabilizers with different molecular weights. 10,11 In the case of WO 3 , it was found that photochromic properties deteriorate in the series of structures: amorphous > hexagonal > monoclinic. 12,13 A similar effect was recorded for MoO 3 .…”

“…The phenomenon of photochromism appears when certain conditions are matched: (a) small particle size (less than 20 nm), (b) phase composition and structure, and (c) doped structures. The size of the resulting structures can be varied using organic stabilizers with different molecular weights 10,11 . In the case of WO 3 , it was found that photochromic properties deteriorate in the series of structures: amorphous > hexagonal > monoclinic 12,13 .…”

Усиление фотохромных свойств MoO3 и WO3 посредством плазменной обработки золей

“…[6][7][8][9]. Изменение размеров и формы наноструктур достигается путем варьирования молекулярной массы стабилизатора [10,11].…”