Room-Temperature Ammonia Detection Using Layered Bi<sub>2</sub>Se<sub>3</sub>/Bi<sub>2</sub>O<sub>3</sub>: A Next-Generation Sensor
Biswajit Das, Sk Riyajuddin, Kaushik Ghosh, Ranajit Ghosh
Abstract
We demonstrate room-temperature NH 3 sensors for the first time using liquid-phase-exfoliated layered n-Bi 2 Se 3 /p-Bi 2 O 3 of four different compositions (Bi 2 Se 3 in %:Bi 2 O 3 in % = 27.1:72.9, 52:48, 64:36, and 77:23) by hydrothermal synthesis for 7, 14, 21, and 28 h which are named as B7, B14, B21, and B28, respectively. Sensor B14 exhibits superior sensing performance within a wide concentration range (5–180 ppm) of NH 3 with high selectivity (among NH 3, acetone, toluene, isopropyl alcohol, methyl amine, ethanol, methanol, and benzene) and a response ( R = I g / I a ) of 8.5 toward 180 ppm due to the maximum interaction between n-Bi 2 Se 3 and p-Bi 2 O 3 . The sensor delivered a response time of 134.5 s and a faster recovery of 23.5 s with a limit of detection of 5 ppm. The sensing mechanism is explained on the basis of experimentally confirmed physisorption (decrement of response from 8.18 to 4.63 with the increase of operating temperature from 30 to 50 °C)-based charge transfer at the adsorption sites on the Bi 2 Se 3 surface and modulation of barrier potential formed between n-Bi 2 Se 3 and p-Bi 2 O 3 . Further, the long-term stability of the sensor over 90 days indicates potential candidature of the material to be used as a next-generation NH 3 sensor at room temperature.