CNT-based sensor array for selective and steady detection of SO2 and NO

Abstract

The accurate detection of NO and SO2 emitted from fossil fuel power plants is critical for realizing the real-time control of clean combustion systems and environmental protection. An array of two CNT-based ionization sensors with different electrode separations is used to detect NO and SO2 in flue gas. The responses of each sensor show a monotone decreasing response, and are obviously separated but almost parallel. The decreasing response is attributed to strong consumption of N2(A3∑u+) and N2(a'1∑u+) in collision with SO2 or NO. And the separated and parallel responses in gas mixture indicates a good selectivity and the ability to simultaneously detect SO2 and NO concentrations with no other means. In addition, the array also have excellent long-term stability due to its non-self-sustaining discharge, which reducing the damage of CNTs caused by electrical breakdown. And the sensor has a fast response and recovery times of 8 s and 7 s, respectively.