检测变压器油中溶解气体的一维二氧化锡纳米纤维气体传感器掺杂改性机理及气敏特性研究

Doping modification could improve the gas sensing properties of SnO2 based gas sensors to fault characteristic gases dissolved in transformer oil. Because its doping and sensing mechanism is imperfect and controversial, some limitations still exist, for instance, low gas response, poor selectivity and stability, which restricts the prevalent application of on-line monitoring devices with SnO2 sensing technology. Our previous experiments indicate that doping modification route has significant influence on the sensing properties of SnO2 based gas sensors, while its effecting law and action mechanism remains to be further proved and discussed. Therefore, this project plans to investigate doping modification mechanism and sensing characteristics of SnO2 based gas sensors with various doping modification routes. One-dimensional SnO2 nanofibers are selected as the sensitive materials, and three most representative doping modification routes, including direct surface decoration, atomic coordination substitution, and lattice interstitial doping are focused in this project. Firstly, based on the density functional theory, three kinds of doping modification models and gas adsorption models are established. Simulating calculations are conducted with the first principle from the atomic and electronic level. Finally, its doping modification mechanism and sensing mechanism to fault characteristic gases are discussed combined with experimental test and theory calculation. This work may lay a solid foundation for developing high-performance SnO2 based gas sensors with the purpose of on-line monitoring dissolved gases in transformer oil, and also provide a new insight to solve some key problems of oxide gas sensors.

掺杂改性可以改善SnO2基气体传感器对油中故障特征气体的气敏性能，但由于掺杂改性机理及气敏响应机理的诸多不明确性，灵敏度低、选择性及稳定性差等难题仍未解决，限制了在线分析技术的推广应用。前期实验研究表明掺杂物的掺杂改性方式对SnO2基气体传感器的气敏性能有重要影响，但其影响规律和作用机制还有待进一步探讨。为此，本项目提出开展基于不同掺杂改性方式的SnO2基气体传感器掺杂改性机理及对油中特征气体的气敏特性研究。运用密度泛函理论建立基于表面直接沉积、原子配位取代、晶格间隙掺杂等不同掺杂改性方式的一维SnO2纳米纤维气敏材料的掺杂改性模型和对油中特征气体的气体吸附模型，并进行第一性原理原子、电子结构信息仿真计算，结合实验测试探究其掺杂改性机理及对油中特征气体的气敏响应机理。本研究将为研制高性能的油中溶解气体在线监测SnO2基气体传感器奠定坚实基础，并为解决氧化物气体传感器的关键难题提供新思路。

气体传感检测技术是油中溶解气体在线监测的核心，直接影响监测系统的准确性、稳定性及使用寿命。项目提出开展基于不同掺杂改性方式的SnO2基气体传感器掺杂改性机理及对油中特征气体的检测特性研究。制备基于表面直接沉积、原子配位取代以及晶格间隙掺杂改性方式的SnO2基气敏材料和元件并测试其对油中特征气体的温度特性、浓度特性、选择性、稳定性等气敏性能。同时基于密度泛函理论建立对应掺杂改性方式的SnO2基气敏材料掺杂改性模型和对油中特征气体的气体吸附模型，并进行第一性原理仿真计算，研究掺杂体系及气体吸附体系的微观原子、电子结构信息。结合实验测试和第一性原理理论计算，探究基于不同掺杂改性方式的SnO2基气敏材料的掺杂改性机制及对油中特征气体的气敏响应机制。取得的主要成果有：.① 针对乙炔C2H2检测，建立了稀土金属钐Sm掺杂SnO2基气敏材料的掺杂改性机制及对C2H2气体的气敏响应机制。表面直接沉积掺杂构型的掺杂形成能最小，为最优掺杂方式，2.5 mol%为最佳掺杂比。2.5 mol% Sm2O3-SnO2气体传感器在检测C2H2时表现出更佳的气敏性能；同时该元件对C2H2表现出良好的选择性，可以将C2H2与CO、H2进行有效区分。.② 针对甲烷CH4检测，建立了贵金属Pd掺杂SnO2基气敏材料的掺杂改性机制及对CH4气体的气敏响应机制。CH4气体的吸附反应更容易发生在Pd2+表面直接沉积掺杂的SnO2(110)面模型中，且吸附后系统更稳定。当Pd2+表面沉积掺杂量为1.5 wt%时，SnO2基传感器对CH4气体的气敏特性最优，该元件对CH4气体的检测极限为1 uL/L的CH4气体，在C2H2、CO、H2共存的情况下，对CH4具有良好的选择性。.③ 针对一氧化碳CO检测，建立了金属铂Pt、镍Ni、锌Zn掺杂SnO2基气敏材料的掺杂改性机制及对CO气体的气敏响应机制。基于表面直接沉积Pt掺杂的SnO2基气敏元件检测CO气体的最佳工作温度更低、检测极限更小、检测灵敏度更高，对于H2、CH4、C2H6、C2H2检测具有较好的选择性。.项目发表SCI等期刊论文24篇，其中ESI高倍引论文2篇，申请发明专利6项，授权2项。研究成果为研制高性能的油中溶解气体在线监测SnO2基气体传感器奠定了坚实基础。