Exploiting Two‐Dimensional Bi 2 O 2 Se for Trace Oxygen Detection

We exploit a high‐performing 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 confirms 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. 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 show 2D Bi 2 O 2 Se is an ideal candidate for trace oxygen detection.