Sensing Mechanism Studies of WO3Nanoplates with an Orthorhombic Crystal Phase to Trimethylamine Gas

For semiconductor gas sensors, surface gas chemical reactions cause resistance changes in bulk semiconductors, and this tight connection between surface chemical reactions and changes in semiconductors could be a challenging opportunity to develop a reasonable theory. In this work, WO3nanoplates were synthesized through a hydrothermal approach and WO3nanoplate sensors also show high sensitivities to trimethylamine (TMA) gas. Both IR and NMR spectra show that this orthorhombic WO3structure has water molecules acting as the coordination solvent. The IR spectra of the samples also demonstrate the existence of W═O bonds. The loss of coordinated water molecules in WO3lattices caused the formation of oxygen vacancies, and the electrons trapped by oxygen vacancies can be effectively stabilized by the W═O conjugate bonds. The coordinated water molecules in WO3lattices and the W═O bonds should be responsible for the high sensing performance of WO3nanoplates. Our observation connected the surface gas chemical affair and the bulk physical one.