Detection of triacetone triperoxide using temperature cycled metal-oxide semiconductor gas sensors

The temperature-dependent sensing properties of metal-oxide semiconductor gas sensors (MOX), based on SnO2 and WO3, to measure triacetone triperoxide (TATP), diacetone diperoxid (DADP), and di-tert-butyl-peroxide (DTBP) and acetone are described. Conductivity measurements in the range from 100 to 400 °C operating temperature show two different reaction pathways on the surface for WO3 sensors. At temperatures below 150 °C organic peroxides react as an oxidizer which leads to an increase in the sensor resistance. Above 200 °C they react as a reducing agent that leads to a decrease of the sensor resistance. This effect is caused by two different, peroxide dependent reaction paths. The unique behavior of WO3-based sensors can be used for selectivity enhancements in temperature cycle operation mode. With this method gas concentrations down to a few ppb are detectable. Scheme of TATP reacting on tungsten oxide semiconductor gas sensor. TATP decomposes and this leads to an increase of the sensor resistance at low temperatures and a decrease of resistance at high temperatures.