The Updated Gas Sensing Performance of in 2 O 3  Porous Nanospheres For Ppb Level Formaldehyde by Doping with Mo

Abstract

Rapidly and highly sensitive detection of formaldehyde (HCHO) at ppb level by using metal oxide semiconductor (MOS) based gas sensor has attracted growing attention due to the urgent need for environmental and health protection. Herein, a molybdenum (Mo) doping strategy was proposed to improve the formaldehyde (HCHO) sensitivity of In2O3 porous nanospheres (PNSs), which enables them to monitor ppb level HCHO at a relatively lower temperature. The Mo-doped In2O3 (Mo-In2O3) PNSs were prepared through a freeze-drying and calcination route by using hydrothermally synthesized In(OH)3 as a precursor. As applied as an active material for detecting HCHO, the Mo-In2O3 PNSs showed some impressive improvements as compared with bare In2O3 counterparts, such as lower operating temperature (300℃ vs 120℃), higher response (17 vs 1.92 for 1 ppm HCHO), the shorter response time (324 s vs 423 s), and better selectivity. Even to 10 ppb HCHO, the Mo-In2O3 sensor can give a response as high as 2.44, revealing its immense potential for detecting ppb level HCHO. The multiple sensitization effects in Mo-In2O3 PNSs as well as their behind mechanism were discussed.

Keywords: Mo-doped In2O3, Low working temperature, HCHO sensor, Trace ppb-level