Ultrasensitive SO2 sensor for sub-ppm detection using Cu-doped SnO2 nanosheet arrays directly grown on chip

Abstract

Ultrasensitive trace detection of toxic and harmful gases has become an important research field with increasing of human needs. This work introduces a chemiresistive type of SO2 sensor based on Cu-doped SnO2 nanosheet arrays (Cu-SnO2 NSAs), which are directly grown on the chip of Au electrodes via a facile homogeneous precipitation method. The vertically-aligned Cu-SnO2 nanosheets with ultrathin thickness (<10 nm) feature a cross-linked structure and semi-open space among these nanosheets. Compared with pure SnO2 NSAs, the Cu-doped (1–5%, molar percent) sensors exhibit significantly improved SO2 detection capability even at sub-ppm level in a dry environment, where SO2 acts as a stronger oxidizing agent than oxygen. In particular, the 1% Cu-SnO2 NSAs show the highest response (91.51, at 6 ppm) and good selectivity toward SO2 gas at an operation temperature of 250 °C, suggesting a promising route to the development of ultrasensitive SO2 sensors. Furthermore, the effects of environment humidity and operation temperature on the SO2 sensing properties of Cu-SnO2 NSAs are investigated.