钙钛矿型CO2气敏材料的第一性原理研究

CO2 gas sensor is needed in many fields to monitor the CO2 concentration. This proposal plans to provide an understanding of the gas sensing process from the level of atomic theory and quantum mechanics. Carbon dioxide is an inert molecule which is difficult to be activated. Its sensitivity needs to be improved, compared with other oxidizing or reducing gas. And then, this proposal chooses the perovskite-type LaMnO3 as the basal material, adjust the acid-base properties of its surfaces to activate the CO2 molecules and achieve the purpose of enhancing the CO2 gas sensitivity. In view of the existing mechanism of gas sensitive cannot well explain the experiment results of CO2 gas sensing, and the theoretical calculation cannot well simulate the real process in the experiment, this proposal plans to give a more real sensing process by pre-adsorbed O2, H2 and H2O etc. on the surface of LaMnO3-based materials before CO2 introduction. Implement this proposal will find out the key parameters affect the CO2 gas sensing properties from the atomic level, provide theoretical guidance for the further development of new gas-sensing materials and provide theoretical explanation for experimental results.

工业、农业等众多领域都需要CO2气体传感器来监测CO2浓度。本申请项目拟采用第一性原理计算，从原子论和量子力学的层面提供对气敏过程的深入了解，研究气敏机理。针对二氧化碳是一种惰性分子，不易活化，与其他氧化性或还原性气体相比，其灵敏度还有待提高，本申请项目选用LaMnO3钙钛矿材料为基础，通过La位和Mn位的部分掺杂、研究不同的晶面、表面缺陷等，调整材料表面的酸碱性，以达到活化CO2分子，提高对CO2气敏性的目的；针对目前CO2的气敏机理还没有一个较全面而公认的理论，理论计算没有很好的模拟真实的气敏过程，本项目拟通过在材料表面预吸附O2、H2或H2O等分子模拟更真实的气敏过程，以解释现有的实验结果，从分子吸附和原子结合等层面和角度深入理解和分析气敏机理。项目的实施将从原子层面找出影响材料对CO2气敏性的关键参数，为进一步开发新型气敏材料提供理论指导，并对气敏实验中的各种实验结果提供理论解释。

构建了合理的LaMnO3基钙钛矿晶体结构模型，找到稳定的晶面，给出CO2在材料表面的吸附位点、吸附构型、电荷转移等情况，为LaMnO3基钙钛矿材料作为CO2气敏材料提供理论依据；对比CO2分子在纯净表面与预吸附O2、H2或H2O分子的表面吸附特性的变化，为材料在复杂环境中的气敏性提供理论指导。在计算结果的指导下，我们对金属氧化物纳米材料的气敏性质进行了一系列的实验研究，合成出一系列气敏性良好的纳米材料。