Mesoporous WN/WO3-composite nanosheets for the chemiresistive detection of NO2 at room temperature

Abstract

Composite materials, which can optimally use the advantages of different materials, have been studied extensively. Herein, hybrid tungsten nitride and oxide (WN/WO[subscript 3]) composites were prepared through a simple aqueous solution route followed by nitriding in NH[subscript 3], for application as novel sensing materials. We found that the introduction of WN can improve the electrical properties of the composites, thus improving the gas sensing properties of the composites when compared with bare WO[subscript 3]. The highest sensing response was up to 21.3 for 100 ppb NO[subscript 2] with a fast response time of ~50 s at room temperature, and the low detection limit was 1.28 ppb, which is far below the level that is immediately dangerous to life or health (IDLH) values (NO[subscript 2]: 20 ppm) defined by the U.S. National Institute for Occupational Safety and Health (NIOSH). In addition, the composites successfully lower the optimum temperature of WO[subscript 3] from 300 °C to room temperature, and the composites-based sensor presents good long-term stability for NO[subscript 2] of 100 ppb. Furthermore, a possible sensing mechanism is proposed. ©2016 Keywords: WN/WO3 composite; nanosheets; gas sensor; NO2; room temperature