Synthesis and improved gas sensing properties of NiO-decorated SnO_2 microflowers assembled with porous nanorods

摘要

Aiming to improve the gas sensing property of SnO_2 by utilizing the advantages of both porous structure and p-n junctions, NiO-decorated SnO_2 microflowers assembled with porous nanorods were successfully prepared via a sacrificial template-assisted synthesis method by using SnC_2O_4 as sacrificial template for porous SnO_2 and Ni(NO_3)_2 as NiO source. Through this method, different amounts of NiO can be homogenously dispersed in porous SnO_2 to form p-NiO-SnO_2 junctions without changing the original flower-like morphology of SnC_2O_4. In the as-prepared flower-like NiO/SnO_2 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/SnO_2 microflowers exhibit a remarkably improved gas sensing performance compared with pristine SnO_2. 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 SnO_2 (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-SnO_2 heterojunction related gas sensing mechanism was discussed.