Ag nanoparticles-modified Fe2O3@MoS2 core-shell micro/nanocomposites for high-performance NO2 gas detection at low temperature

Abstract In this work, a success was achieved in synthesizing the core-shell micro/nanostructure constructed by α-Fe2O3 microdrums and few-layered MoS2 nanosheets using a simple solvothermal route without the involvement of any exfoliation process. The preparation of core-shell structure and Ag nanoparticle modification enhanced sensor performance significantly. The response of the Ag–Fe2O3@MoS2 sensor to 5 ppm NO2 reached as high as 202.2% with response and recovery times of 81 and 355 s, respectively, which is about 11.8 times higher than that of the MoS2 sensor (17.1%). The Ag–Fe2O3@MoS2 sensor showed a great sensitivity to NO2 against CO, H2, NO2, and NH3, but was not responsive to various volatile organic compounds (VOCs) such as ethanol, methanol, acetone, and isopropyl alcohol, indicating that the sensor can resist the interference caused by VOCs. The enhanced gas sensing performance can be attributed to the synergistic effect of the core-shell structure and the chemical sensitization as well as the electron sensitization effects of noble metal Ag, which was discussed in detail.