一维纳晶锰基复合氧化物的气敏特性与机理研究

Semiconducting complex metal oxides have been a focus of gas sensing materials research. The synthesis of one-dimensional (1D) manganese-based complex oxide nanostructures can perform unidirectional electrical conduction to reduce the electrical signal loss, therefore, it is expected to get high-quality new gas-sensing materials. However, it is still a challenge to find a universal strategy for fabricating the 1D complex metal oxide nanostructures. In this project, we will synthesize a series of 1D nanocrystalline alkaline earth metal manganese oxides A-Mn-O (A= Ca, Sr, Ba) gas-sensing materials by the environmentally friendly molten-salt method. The effect of synthetic conditions on the structure and morphology of samples and their growth mechanism will be studied for the purpose of developing universal synthetic method for 1D complex metal oxide nanostructures. More work involving the detailed investigation of the sensitivity, resolution, response/recovery time, and stability of the 1D A-Mn-O samples toward O2, CO, and NOx gases, as well as the relationship between structure, morphology, defect, and gas-sensing properties of samples. At the same time, the electronic structure and gas adsorption on the surface of the 1D A-Mn-O samples will be investigated using first-principles density functional theory calculations. The gas sensing mechanism will also be studied by using a combined theoretical and experimental approach, in order to provide theoretical and experimental basis for the design of nano gas sensors in a higher level.

复合金属氧化物半导体材料是气敏材料研究领域的一个研究热点，设计合成锰基复合氧化物一维纳米结构，可以实现电子的单向导电、减少信号损耗，有望获得性能优异的新型气敏材料。但复合金属氧化物一维纳米结构的制备，目前仍是纳米合成技术中的一个难点。本项目拟采用环境友好的融盐法合成系列碱土金属锰氧化物A-Mn-O（A = Ca, Sr, Ba）一维纳晶气敏材料，研究合成条件与产物结构、形貌之间的关系及其形成机制，发展一维纳米复合金属氧化物气敏材料的普适性制备技术；系统研究 A-Mn-O一维纳晶样品对O2、CO、NOx等气体的灵敏度、分辨率、响应-恢复时间以及稳定性，并总结结构、形貌、缺陷与性能之间的关系，阐明其基本规律；同时，利用第一性原理计算模拟样品表面和表面的气体吸附，理论与实验相结合，探讨其气敏机理，为更高层次上设计制备纳米气敏传感器提供实验基础和理论依据。

设计合成锰基复合金属氧化物一维纳米结构，可以实现电子的单向导电、减少信号损耗，有望获得性能优异的新型气敏材料。但复合金属氧化物一维纳米结构的制备，目前仍是纳米合成技术中的一个难点。通过本课题的实施，我们已取得以下几个方面的研究结果：（1）通过熔盐法结合离子交换法制备了Na0.44MnO2, BaMn8O16, SrMn3O6等系列锰氧化物一维纳米晶，并研究了其形成机制。基于此制备技术，并成功合成了系列钛酸盐和铌酸盐一维纳米结构。（2）研究结果表明锰基复合金属氧化物一维纳米晶对乙醇、甲醇、O2、CO2等气体具有不同程度的敏感特性，且材料结构和形貌对其气敏性能具有明显的影响。（3）采用化学气相沉积法、水热法等制备了In2O3、ZnO-SnO2系列半导体金属氧化物一维纳米结构，测试结果表明其对甲烷、CO、NO2等气体具有良好的敏感度。（4）利用第一性原理对C参杂ZnO的电子结构进行了理论计算。以上研究结果为后续在更高层次上设计制备纳米气敏传感器提供了实验基础和理论依据。