High triethylamine-sensing properties of NiO/SnO2 hollow sphere P-N heterojunction sensors

Triethylamine (TEA) gas sensor with high response and selectivity was fabricated successfully with PN heterojunction consisted of n-type SnO2 hollow spheres and p-type NiO nanoparticles. SnO2 hollow spheres were synthesized by a template-assisted hydrothermal method. The NiO/SnO2 P-N junction was formed by depositing NiO nanoparticles onto the surface of SnO2 hollow sphere sensors via a pulsed laser deposition (PLD) process. The response of NiO/SnO2 sensor is up to 48.6 when exposed to 10 ppm TEA gas, which is much higher than that of pristine SnO2 hollow spheres and most of other reported TEA sensors. The detection limit can also be as low as 2 ppm-level. Moreover, the optimal operating temperature is down to 220 °C, and 40 °C lower than that of the pristine SnO2 hollow sphere sensor. These good sensing performances mainly attribute to the formation of depletion layer at the P-N junction interface in the NiO/SnO2 sensor, which makes great variation of resistance in air and TEA gas. Thus, the combination of n-type SnO2 hollow spheres and p-type NiO nanoparticles provides an effective strategy to design new TEA gas sensors.