Competitive adsorption of gases dissolved in transformer oil on Co-doped ZnO (0001) surface

The use of gas sensors to monitor gases dissolved in transformer oil is of great value to prevent safety issues of power grid. As a part of developing high performance gas sensor, the deeply sensing mechanism in material aspect study has great guiding significance. In this paper, a new surface adsorption model is proposed which provides an approach to achieve the improvement of the gas-sensing performance of Co-doped ZnO sensor theoretically. Utilizing first-principle density functional theory, the adsorption properties of six main characteristic fault gases (C2H2, CO2, CH4, C2H4, CO, and H-2) on Co-doped ZnO (0001) surface were systemically investigated which indicated that H-2 and CH4 molecules were physically adsorbed, whereas CO, CO2, C2H2, and C2H4 were chemisorbed. In addition, using the as-prepared Co-doped ZnO material, the gas-sensing response for these fault gases were experimentally measured, which matches well with the theoretical analysis. This work reveals the gas-sensing performance of Co-doped ZnO composites in microscopic. It lays the foundation for the preparation of gas sensors to serve for monitoring the condition of power transformers. (C) 2017 Elsevier B.V. All rights reserved.