First polyoxometalate-modified SnS2 composite nanostructure gas sensor toward enhanced sensitivity and high selectivity for NO2 detection

In this work, the first polyoxometalate modified SnS2 gas sensor are synthesized by convenient hydrothermal method and applied for detecting NO2 gas in the air. Under optimal test condition, the SnS2-3%PW12 sensor delivered a gas sensing response of 3.9 to 50 ppm NO2 gas, which is 2.3 times higher than pure SnS2 sensor. Fast response/recovery time (24/30 s) and low limit-of-detection (53 ppb) were also exhibited. Repeatability, long-term stability and humidity resistance were both good. The mechanism analysis shows that PW12, as an electron-transport mediator, can trap electrons in the conduction band of SnS2, generate shallow electron traps, and effectively inhibit the recombination of electrons and holes in SnS2, thereby enhancing gas sensing performance for NO2 detection. This paper introduces a new way of developing high sensitivity SnS2-based gas sensors by introducing polyoxometalates as electron acceptors.