Study on enhanced H2 gas sensing characteristics of CuO-SnO2 nanostructures

In the past decades, the application of nanostructures and nanotechnology has attracted intensive attention in many fields from electronic devices to chemical sensors. The monitoring of toxic or inflammable gases has been increasingly important for humans, environment and various areas. In the power system field, power transformers are important equipment of electricity transmission and distribution, and its operation condition is associated with the safety of power system. If the power transformers break down, there will be a huge lose in national economic. Hydrogen (H₂) is one of the main fault characteristic gases dissolved in transformer oil, which can indicate the high energy discharge, spark discharge, partial discharge and partial oil overheating. The gas sensor technology is the key of on-line monitoring trace amount of gases. This paper made a research on the detection characteristics of CuO-SnO₂ gas sensor to the H₂ gas dissolved in transformer oil. In this study, a facile hydrothermal method was adopted to fabricate SnO₂ and CuO-SnO₂ nanoparticles. The CuO content was chosen as 5mol-% (sample 1), 10mol-% (sample 2) and 15mol-% (sample 3). Microstructures and surface morphologies for all samples were characterised by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). Then the gas sensing mechanism of gas sensor was analyzed. The results proved that: A lot of p-n heterojunction would form which change the gas sensing properties of composite SnO₂-based gas sensor to hydrogen; compared with the SnO₂ gas sensor, the CuO-SnO₂ performed better sensitivity and quicker response to the H₂,and also kept a good linearity and stability. The results offer a new thought to study the application of composite SnO₂-based gas sensor on det- cting the gases dissolved in transformer oil on line and represent an advance of heterojuction nanostructures in further enhancing the functionality of gas sensors towards H₂.