Gas sensing properties of ZnO-SnO 2 nanostructures towards CO in transformer oil

Power transformer is an important equipment to transport and deliver the electric energy in the power system. It will result in huge damage of national economy while the transformers break down. On-line monitoring the dissolved gases in oil is one of the effective methods to improve the security and reliability of the power system. CO is the one of main failure characteristic gases in the transformer oil. It's significant to monitor on-line and analyze CO gas for the power transformer's safe operation. The key of on-line monitoring is the gas sensor technology. One-dimensional (1D) semiconductor metal oxide nanostructures have attracted increasing attention in electrochemistry, optics, magnetic, and gas sensing fields for the good properties. N-type low dimensional semiconducting oxides such as SnO 2 and ZnO have been known for the detection of inflammable or toxic gases. In this paper, we fabricated the ZnO-SnO 2 and SnO 2 nanoparticles by hydrothermal synthesis. Microstructure characterization was performed using X-ray diffraction (XRD) and surface morphologies for both the pristine and doped samples were observed using field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). Then we made thin film gas sensor to study the gas sensing properties of ZnO-SnO 2 and SnO 2 gas sensor to CO. A systematic comparison study reveals an enhanced gas sensing performance for the sensor made of SnO 2 and ZnO towards CO over that of the commonly applied undecorated SnO 2 nanoparticles. The improved gas sensing properties are attributed to the size of grains and pronounced electron transfer between the compound nanostructures and the absorbed oxygen species as well as to the heterojunctions of the ZnO nanoparticles to the SnO 2 nanoparticles, which provide additional reaction rooms. The results represent an advance of compound nanostructures in further enhancing the functionality of gas sensors, and this facile method could be applicable to many sensing materials, offering a new avenue and direction to detect gases of interest based on composite tin oxide nanoparticles.