Au Functionalized SnS2 Nanosheets Based Chemiresistive NO2 Sensors

Layered Au/SnS2 nanosheet based chemiresistive-type sensors were successfully prepared by using an in situ chemical reduction method followed by the hydrothermal treatment. SEM and XRD were used to study the microscopic morphology and crystal lattice structure of the synthesis of Au/SnS2 nanomaterials. TEM and XPS characterization were further carried out to verify the formation of the Schottky barrier between SnS2 nanosheets and Au nanoparticles. The as-fabricated Au/SnS2 nanosheet based sensor demonstrated excellent sensing properties to low-concentrations of NO2, and the response of the sensor to 4 ppm NO2 at 120 °C was approximately 3.94, which was 65% higher than that of the pristine SnS2 (2.39)-based sensor. Moreover, compared to that (220 s/520 s) of the pristine SnS2-based sensor, the response/recovery time of the Au/SnS2-based one was significantly improved, reducing to 42 s/127 s, respectively. The sensor presents a favorable long-term stability with a deviation in the response of less than 4% for 40 days, and a brilliant selectivity to several possible interferents such as NH3, acetone, toluene, benzene, methanol, ethanol, and formaldehyde. The Schottky barrier that formed at the interface between the SnS2 nanosheets and Au nanoparticles modulated the conducting channel of the nanocomposites. The “catalysis effect” and “spillover effect” of noble metals jointly improved the sensitivity of the sensor and effectively decreased the response/recovery time.