Synthesis and improved gas sensing properties of NiO-decorated SnO2 microflowers assembled with porous nanorods

Aiming to improve the gas sensing property of SnO2 by utilizing the advantages of both porous structure and p-n junctions, NiO-decorated SnO2 microflowers assembled with porous nanorods were successfully prepared via a sacrificial template-assisted synthesis method by using SnC2O4 as sacrificial template for porous SnO2 and Ni(NO3)2 as NiO source. Through this method, different amounts of NiO can be homogenously dispersed in porous SnO2 to form p-NiO/n-SnO2 junctions without changing the original flower-like morphology of SnC2O4. In the as-prepared flower-like NiO/SnO2 architecture, the porous nanorods are about 2 μm in length and 100-200 nm in diameter and are constructed by numerous loosely stacked nanoparticles with the size about 20 nm. Gas sensing tests indicate that the NiO/SnO2 microflowers exhibit a remarkably improved gas sensing performance compared with pristine SnO2. The response of 1NTO (with the optimal NiO content of 1 mol%) to 1000 ppm ethanol is as high as 576.5, which is much higher than that of the pristine SnO2 (315.5). Besides of high sensitivity, the 1NTO sensor also exhibits excellent linearity in a wide range of ethanol concentration (50-1000 ppm) as well as good repeatability and durability. The p-NiO/n-SnO2 heterojunction related gas sensing mechanism was discussed.