层状前驱体法构筑半导体异质结及其光激发气敏性质

Developing gas sensor is very important for protecting envionment and the critical part is to obtain gas sensitive materials with high properties. This project aims at the general problem that metal oxide semiconductor gas sensitive materials normally have the high working temperature. It is proposed to prepare the light-stimulated gas sensitive materials using layered double hydroxides (LDH) as precursors and using visible light instead of heat source to lower down the working temperature. According to the semiconductors' forbidden band width, one can design the metal elements in LDH which can be calcined into layered double oxides (LDO) with semiconductor heterostructures. The photo induced charges can be separated efficiently and the visible light responsible gas sensing materials will be developed. To prepare LDHs with specific morphology and structures based on templates, which is followed by a calcined process to obtain LDO with nano hierarchical structures. Therefore, the gas sensing properties will be improved with the aid of visible light excitation. By a nonmetal doping of LDO, the forbidden band width will be tuned and the spectral adsorption domain will be expanded. The efficiency of light excitation gas sensing properties will be improved also. By means of some modification approaches, such as surface deposition with precious metals, composite with organic conductive materials etc., the electronic structures of the materials will be changed and the light-stimulated efficiency will be advanced. The gas sensing mechanism stimulated by light stimulates will be studied and the regularities between the structures and the properties will be summarized also. By conducting this project, the light-simulated gas sensitive materials will be developed. To utilize the sunlight effectively, this project will provide the theoretical basis to develop the light stimulated gas sensor technology.

气敏传感器的开发对保护环境极其重要,而获得高性能的敏感材料是关键。本项目针对氧化物半导体气敏材料普遍存在工作温度较高的问题，拟利用双金属氢氧化物（LDHs）前驱体法制备光激发气敏材料，实现可见光源代替热源，从而降低工作温度。根据半导体的禁带宽度设计元素组成，经原位拓扑焙烧构筑具有半导体异质结的复合金属氧化物（LDO），并借助可见光激发来实现光生电荷的有效分离，发展可见光响应的气敏材料；采用模板法制备具有不同形貌的LDHs，进而制备LDO纳米多级结构，提升气敏性能；对LDO进行非金属掺杂，调变异质结的禁带宽度，扩展光谱吸收范围，增强光响应能力；通过LDO表面沉积贵金属、复合有机半导体等方式改变半导体异质结的电子结构，提高光激发气敏效率；研究LDO复合材料的光激发气敏机理，总结构效关系。通过本项目的实施，开发高性能的光激发气敏材料，为有效利用太阳光，发展光激发气敏技术提供理论及实验基础。

本课题主要基于水滑石前驱体开发和制备了多种气敏材料，特别是光激发辅助降低气敏材料工作温度的研究。首先通过元素组成设计，已采用单源水滑石前驱体焙烧法制备了7种复合金属氧化物材料。通过研究复合物内部的异质结相互作用，已归纳出材料组成对材料气敏性质的影响规律及光激发刺激对材料气敏性质的影响。结果表明光辐照的引入降低了特定气敏传感器的工作温度，为制备低温工作的气敏传感器提供了途径。其次以陶瓷管原位生长了ZnNi及ZnIn两种水滑石材料，以FTO玻璃为基底生长了ZnIn水滑石材料，并将以上水滑石材料为前驱体焙烧得到具有纺锤形貌及花瓣形貌的复合氧化物多级结构，已归纳出形貌对材料气敏性能的影响及光照激发刺激对材料气敏性质的影响。特别是ZnIn多级结构在接近室温的工作温度下，气敏元件在光激发条件下对200 ppm三乙胺的响应值达到了80，已经超过传统加热型复合氧化物对同浓度三乙胺的响应值，实现了于接近室温状态对三乙胺的检测。再次，以复合金属氧化物材料的表面改性研究中选用有机表面活性剂插层的水滑石为前驱体，制备有非金属碳掺杂的复合氧化物ZnO/In2O3，考察了材料掺杂非金属后的气敏性质。进一步拓展研究，制备了聚苯胺插层的水滑石材料，研究了不同金属组成的水滑石对水蒸气的敏感行为的影响，研究表明锂离子型水滑石对湿度的敏感性最佳。另外，以水滑石为前驱体焙烧制备得到的CdO/Al2O3复合氧化物，比共混无机盐的方法得到的复合氧化物具备更高的敏感性能。此外，也发现并制备得到了其他类型的湿敏材料，如CdS/PANI复合材料。除了气湿敏应用材料的制备研究以外，我们进行了压敏材料的拓展研究，已制备出柔性可穿戴的压敏材料。本课题以第一作者或者通讯作者发表SCI论文8篇，申请专利4项。本课题以水滑石为前驱体得到的氧化物材料具有更好的元素分布性，通过元素的组合得到具有优异性能敏感材料，拓宽了水滑石材料的应用。另外光激发辅助的方法为开发新型室温下可工作的传感器提供了新的途径。