Abstract
Modern chemical production processes often emit complex mixtures of gases, including hazardous pollutants such as NO(2). Although widely used, gas sensors based on metal oxide semiconductors such as WO(3) respond to a wide range of interfering gases other than NO(2). Consequently, developing WO(3) gas sensors with high NO(2) selectivity is challenging. In this study, a simple one-step hydrothermal method was used to prepare WO(3) nanorods modified with black phosphorus (BP) flakes as sensitive materials for NO(2) sensing, and BP-WO(3)-based micro-electromechanical system gas sensors were fabricated. The characterization of the as-prepared BP-WO(3) composite through X-ray diffraction scanning electron microscopy and X-ray photoelectron spectroscopy confirmed the successful formation of the sandwich-like nanostructures. The result of gas-sensing tests with 2-14 ppm NO(2) indicated that the sensor response was 1.25-2.21 with response-recovery times of 36 and 36 s, respectively, at 190 °C. In contrast to pure WO(3), which exhibited a response of 1.07-2.2 to 0.3-5 ppm H(2)S at 160 °C, BP-WO(3) showed almost no response to H(2)S. Thus, compared with pure WO(3), BP-WO(3) exhibited significantly improved NO(2) selectivity. Overall, the BP-WO(3) composite with sandwich-like nanostructures is a promising material for developing highly selective NO(2) sensors for practical applications.