Hydrothermal synthesis of assembled sphere-like WO3 architectures and their gas-sensing properties

Unique assembled sphere-like WO3 architectures were successfully synthesized through a facile hydrothermal method in the presence of malic acid followed by subsequent heat treatment. We found that malic acid played a significant role in governing morphologies of WO3·xH2O precursors during hydrothermal process. A possible formation mechanism was also proposed in detail. Experimental results showed that the optimized hydrothermal precursor could be dehydrated to mixed composition of hexagonal and monoclinic WO3 with the unique sphere-like porous architecture after being annealed at 400 °C for 2.5 h. Besides, gas-sensing measurement indicated that the well-defined 3D assembled sphere-like architectures exhibited the highest sensor response to ethanol at the optimal temperature of 250 °C among the samples.

Graphical abstractWe have prepared unique three-dimensional assembled sphere-like WO3 architectures successfully via a facile hydrothermal method followed by a subsequent heat treatment. The well-defined porous structures exhibit novel gas-sensing properties to ethanol.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Unique assembled sphere-like WO3 architectures are successfully obtained. ► Malic acid is introduced as an assembling and structure-directing agent to controllable synthesis of WO3 architectures. ► The well-defined sphere-like WO3 architectures exhibit excellent gas-sensing properties to ethanol. ► The malic acid presented in current experiment may provide inspiration for controllably synthesizing other metals oxide.