Nanoplasmonic NO2 sensing with a Au-WO3 Nanocomposite

Air pollution is one of the largest environmental risk factors causing severe health problems all over the world. In order to take a fast and decisive action against this serious threat, real-time monitoring is desirable.... [ view full abstract ]

Air pollution is one of the largest environmental risk factors causing severe health problems all over the world. In order to take a fast and decisive action against this serious threat, real-time monitoring is desirable. Presently, conventional instrumentation for highly accurate air quality monitoring exists, however it is expensive, stationary and complex. Here, we are presenting an air quality sensor based on indirect nanoplasmonic sensing [1], with the potential to enable real time monitoring of air pollutants at the ppb level. Our sensor is initially optimized for NO₂ detection, since NO₂ is identified as one of the most toxic and corrosive pollutants. In our present design, an array of Au nanodisks is used as plasmonic signal transducer and a thin sputtered WO₃ thin film on top as the active and selective layer. In our study, we investigated the effects of microstructure and thickness of the WO₃ layer, as well as the size of the plasmonic particles, on the sensitivity towards NO₂. In order to mimic a realistic sensing environment, we also conducted our measurements in the presence of CO, CO₂ and humidity. Our results show that with materials grown under optimized conditions our sensors exhibit an NO₂ detection limit in the ppb range, as well as very low cross-sensitivity towards CO, CO₂ and H₂O.

 [1] Larsson E. M. et al Science 2009, 326, 1091-1094.