Competitive adsorption of gases dissolved in transformer oil on Co-doped ZnO (0 0 0 1) surface

Abstract 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 (C 2 H 2 , CO 2 , CH 4 , C 2 H 4 , CO, and H 2 ) on Co-doped ZnO (0 0 0 1) surface were systemically investigated which indicated that H 2 and CH 4 molecules were physically adsorbed, whereas CO, CO 2 , C 2 H 2 , and C 2 H 4 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.