Fast responding and recovering of NO2 sensors based on Ni-doped In2O3 nanoparticles

Abstract

In this work, Ni-doped In2O3 nanoparticles were successfully fabricated via a simple metal-organic framework-derived solvothermal method. The synthesized Ni-In2O3 exhibited as ultrafine nanoparticles with an average size of 13 nm. Gas sensing test results demonstrated that the sensor composed of Ni-doped In2O3 (2 mol%) nanoparticles showed fast response/recovery properties, and the response and recovery speeds toward 10 ppm NO2 were 2 and 2 s, respectively. Furthermore, the response value to 10 ppm NO2 was about 70 at the optimum working temperature of 200 °C exhibiting high sensitivity of the sensors. Additionally, the sensor indicated a superior low detection limit of 5 ppb. These characteristics make Ni-doped In2O3 nanoparticles a desiring candidate for rapid detection of NO2. The possible mechanism of enhanced sensing properties was discussed in detail. The Debye-scale nanoparticles furnish abundant adsorption sites. High oxygen vacancies content provides more electrons to accelerate NO2 excitation. Furthermore, the catalytic action of Ni2+ improved the response/recovery speed. The Ni-doped In2O3 nanoparticles are reasonable to be an ideal substitution for fabricating rapid NO2 detection devices in the future.