Reasonable construction of 2D porous NiO/Co3O4 nanosheets for efficient detection of xylene

P-type semiconductor materials with multivalent characteristics and high catalytic activity have attracted considerable interest for efficient detection of low reactive gases. In this paper, the NiO/Co3O4 nanocomposites with 2D porous sheet-like structure are synthesized through a facile hydrothermal route and following annealing treatment. The gas sensing test shows that the 6 wt% NiO/Co3O4 based sensor exhibits highest response (S = 12.27) to 100 ppm xylene at a relatively low temperature (140 ℃), which is about 3.74 times higher than that of Co3O4. Furthermore, the sensor also manifests a good selectivity and long-term stability. The enhanced sensing performance is attributed to the high specific surface area and the formation of p-p heterojuntions. The charge density difference images directly show that the electrons are mainly transferred from the interface of the NiO/Co3O4 heterostructure to the hydrogen ions in the xylene molecule, and the charge density near the adsorption region is significantly larger than that of the pure Co3O4 model. The research results further clarified the response mechanism of xylene.