(384a) Cu3n Sensors for Detecting the Air Pollutant NO2 at Parts-per-Billion Levels

In our current society, the quality of the air that we breath has become a major concern. Urbanization, industrial plants and emissions from transportation are all part of the main contributors to the decline of air quality. NO₂ is particularly problematic as it is a harmful secondary pollutant in presence with O₃ and directly affects human health. For that reason, its exposure limits are set in the parts-per-billion (ppb) levels by the World Health Organization. An effective NO₂ sensor would need to measure ppb concentration, be selective over many confounders, respond and recover fast, be robust to humidity and operate at low temperatures to limit the energy consumption. Chemoresistive metal oxides (MOx) are widely used for this task as they fulfil greatly some of those criteria (excellent sensitivity and low response and recovery times), however, they generally suffer from poor selectivity and high operating temperature. Here, we demonstrate the selective sensing of ppb-level NO₂ concentration in air at 50% relative humidity with highly porous Cu₃N films. The novel synthesis pathway [1] combines the aerosol deposition of a highly porous CuO film, followed by a dry nitridation to yield porous Cu₃N sensors. The sensor detects NO₂ down to a few ppb at 75 °C with excellent selectivity over aromatics, alkanes, alcohols, ketones and H₂ amongst others. As such sensors can be miniaturized and are low-cost, these can be applied as networks to provide distributed air quality assessment.

Reference:

1. Güntner, A.T.; Wied, M.; Pineau, N.J.; Pratsinis, S.E., Sci. 2020, 7 (7), 1903390.