Exploiting Two-Dimensional Bi2O2Se for Trace Oxygen Detection.

Two-dimensional (2D) materials host great potential for environmental gaseous molecules detection in the age of emerging Internet of things owing to their fascinating electronic properties, large surface-to-volume ratio and feasibility to high integration. However, it remains a challenge to develop trace oxygen sensing 2D materials and devices with low detection limit at sub-ppm range. Here, we exploit a high-preforming resistive-type trace oxygen sensor based on 2D high-mobility semiconducting Bi 2 O 2 Se nanoplates. Scanning tunneling microscopy combined with first-principle calculations proves an amorphous Se atomic layer formed on the surface of 2D Bi 2 O 2 Se exposed to oxygen, which contributes to larger specific surface area and abundant active adsorption sites. Such 2D Bi 2 O 2 Se oxygen sensors have remarkable oxygen-adsorption induced variations of carrier density/mobility, and exhibit an ultrahigh sensitivity featuring minimum detection limit of 0.25 ppm, long-term stability, high durativity, and wide-range response to concentration up to 400 ppm at room temperature. Moreover, 2D Bi 2 O 2 Se arrayed sensors integrated in parallel form are found to possess an oxygen detection minimum of sub-0.25 ppm ascribed to an enhanced signal-to-noise ratio. These advanced sensor characteristics involving ease integration reveal 2D Bi 2 O 2 Se is an ideal candidate for trace oxygen detection.