掺杂半导体纳米带表面/界面调控与室温氢敏性能的优化机理研究

Due to the high working temperature, poor selectivity, and slowly room-temperature response/recovery speed for the traditional semiconductor based hydrogen sensor, this proposal intends to improve the hydrogen sensing performance and study the sensing mechanism of modified MoO3 nanoribbons and their composite with the methods of doping with Fe elements and optimizing the junction structure. Firstly, we study the controllable synthesis of Fe-doped MoO3 nanoribbons and their composite with layered MoS2. Then the effect of the type of Fe elements and their concentrations on the electronic structure of the nanoribbons and absorbed behavior of oxygen/hydrogen on the nanribbon surface is explored through the theoretical calculation and. The gas sensing of the Fe-doped MoO3 nanroribbons will be also studied in experiments. Based on these, the relationship among the Fe elements, their concentrations, and the gas sensing performance will be analyzed. Thirdly, the Fe-doped MoO3 nanoribbons will be composited with layered MoS2 to modify the junction structure in the sensing layer. The adsorption, diffusion, reaction, and desorption behavior of oxygen/hydrogen gas at the material surface and junction interfaces in the composite will be investigated to build the kinetic model of the room-temperature hydrogen sensing behavior. Finally, the optimization mechanism of hydrogen sensing through modifying the junction interface will be revealed. Moreover, a fast, highly-sensitive, and selective room-temperature gas sensing element will be obtained. The smooth implementation of this proposal will provide theoretical and experimental basis for the research and development of hydrogen gas sensor systems and will promote the improvement in the hydrogen sensor with independent intellectual property right and the development of related fields in hydrogen.

针对传统半导体氢气传感器工作温度高、选择性差和室温响应恢复慢等问题，本项目拟从掺杂调控表面缺陷和界面结构优化两方面出发，进行掺杂氧化钼纳米线及其复合材料室温氢敏性能的优化与机理研究。首先，研究Fe掺杂氧化钼纳米带及其硫化钼复合材料的可控制备技术；其次，通过理论计算分析Fe掺杂及其浓度对纳米带电子结构、表面氧/氢吸附行为的影响，并从实验上研究Fe掺杂及其浓度对纳米带氢敏性能的影响规律，探索Fe掺杂与室温氢敏性能的关联性；第三，通过Fe掺杂纳米线与硫化钼的复合改变敏感层界面结构，探索氢和氧在复合材料表面、界面处的吸附、扩散、反应和脱附行为，构建室温氢敏响应动力学模型，揭示界面调控对半导体纳米材料室温氢敏性能的优化机制，获得快速、灵敏且选择性优异的气体敏感元件。项目的顺利实施对氢气传感器的发展与应用具有重要理论和实际意义，有望推动我国自主知识产权氢气传感器的进步和氢能相关领域的安全发展。

氢气是一种清洁和理想的能源载体，如何制备高品质氢气传感器以保证氢能源的安全使用，成为近年来的研究热点。课题组制备了纯净MoO3纳米带，Fe掺杂MoO3纳米带和MoS2纳米片修饰的掺杂MoO3纳米带等敏感材料，通过气氛退火、掺杂和异质结调控了MoO3的室温氢敏性能，成功获得了具有优异室温氢敏性能的响应元件。本项目主要的研究内容包括四个方面：（1）通过水热法成功制备了尺寸均匀[001]取向的MoO3纳米带，平均长度和平均厚度分别约为20 μm和270 nm。系统研究了气氛退火对其室温氢敏性能的影响规律，结果发现300 °C退火所得样品中不饱和Mo5+含量最高，约为24.7%。同时，该样品室温下1000 ppm H2的响应灵敏度也最高，约为17.3，是未处理MoO3的3倍。（2）通过CASTEP计算了Fe掺杂MoO3纳米材料的稳定结构并从理论上研究了其氢敏响应行为。环境中的O2能沿着Y轴方向在氧空位处形成稳定的化学吸附，并从Fe-MoO3表面捕获电荷（~ 0.2 e），使Fe-MoO3中的载流子浓度降低；并且表面化学吸附的O2会与引入的H2发生氧化还原反应生成H2O分子，释放的电荷（1.01 e）使Fe-MoO3中的载流子浓度增加，实现对H2的敏感探测。（3）成功制备了Fe掺杂MoO3纳米带并发现Fe掺杂含量对其室温氢敏性能影响显著。当Fe掺杂含量为6 at%时，掺杂MoO3纳米带在室温下对1000 ppm H2响应性能最优，响应灵敏度约为26.3。由于Fe3+与Mo6+价态不同，Fe掺杂提升了MoO3纳米带表面氧空位含量。同时，掺杂后材料的比表面积增大也有利于改善其室温氢敏性能。（4）系统研究了MoS2纳米片修饰的Zn掺杂MoO3纳米带的可控制备及其室温氢敏的影响。结果表明MoS2纳米片的负载量对复合材料的形貌和氢传感性能具有重要影响。在室温下，MoS2纳米片含量最优的复合材料对500 ppm H2的响应灵敏度为28.91，响应/恢复时间为24.6 s/18.5 s。复合材料高的比表面积、异质结构和势垒高度的有效调制是复合材料氢传感性能提高的主要原因。上述研究为提高半导体氧化物基室温氢敏性能提供了依据，并为开发高品质氢气传感器提供了参考。