UV enhanced NO2 gas sensing at room temperature based on coral-like tin diselenide/MOFs-derived nanoflower-like tin dioxide heteronanostructures

In this paper, a coral-like tin diselenide/MOFs-derived flower-like tin dioxide (SnSe2/SnO2) nanocomposite film sensor was fabricated by hydrothermal method for NO2 gas detection. Many characterization methods were used to examine the structural composition and micro-morphology of SnSe2, SnO2, and SnSe2/SnO2 samples. At room temperature, the SnSe2/SnO2 composite film sensor had a higher response to 20 ppm NO2 gas when the mass ratio of SnSe2 and SnO2 was 1:2. A series of experiments were performed to investigate the NO2 sensing properties of this sensor. The results of gas-sensing tests indicated that the SnSe2/SnO2 (1:2) nanocomposite sensor had excellent NO2 gas sensitivity performance, better linearity and selectivity compared with pristine SnSe2 and SnO2 film sensors. In particular, the response value of the SnSe2/SnO2 nanocomposite sensor towards 20 ppm NO2 gas was obviously improved from 7.4 to 12.6 under UV illumination, and the response/recovery times towards 10 ppm NO2 gas were shortened from 110 s/160 to 80 s/144 s. The possible NO2 sensing mechanism was related to the heterostructure between n-type SnSe2 and n-type SnO2 nanomaterials, and at the same time, we proposed that photoelectrons excited by UV light could improve the sensing characteristics of the SnSe2/SnO2 nanocomposite towards NO2 gas.