A nanoengineered conductometric device for accurate analysis of elemental mercury vapor

We developed a novel conductometric device with nanostructured gold (Au) sensitive layer which showed high-performance for elemental mercury (Hg0) vapor detection under simulated conditions that resemble harsh industrial environments. That is, the Hg0 vapor sensing performance of the developed sensor was investigated under different operating temperatures (30-130 °C) and working conditions (i.e., humid) as well as in the presence of various interfering gas species, including ammonia (NH3), hydrogen sulfide (H2S), nitric oxide (NO), carbon mono-oxide (CO), carbon dioxide (CO2), sulfur dioxide (SO2), hydrogen (H2), methane (CH4), and volatile organic compounds (VOCs) such as ethylmercaptan (EM), acetaldehyde (MeCHO) and methyl ethyl ketone (MEK) among others. The results indicate that the introduction of Au nanostructures (referred to as nanospikes) on the sensor's surface enhanced the sensitivity toward Hg0 vapor by up-to 450%. The newly developed sensor exhibited a limit of detection (LoD) (∼35 μg/m3), repeatability (∼94%), desorption efficiency (100%) and selectivity (∼93%) when exposed to different concentrations of Hg0 vapor (0.5 to 9.1 mg/m3) and interfering gas species at a chosen operating temperature of 105 °C. Furthermore, the sensor was also found to show 91% average selectivity when exposed toward harsher industrial gases such as NO, CO, CO2, and SO2 along with same concentrations of Hg0 vapor in similar operating conditions. In fact, this is the first time a conductometric sensor is shown to have high selectivity toward Hg0 vapor even in the presence of H2S. Overall results indicate that the developed sensor has immense potential to be used as accurate online Hg0 vapor monitoring technology within industrial processes.