Nb2O5纳米线网络的室温氢敏及其修饰增强机理研究

It's of academic significance and wide potential applications to in-situ detect hydrogen with low concentration fast and accurately. In view of the low hydrogen sensitivity and slow response speed at room temperature of semiconductor materials at present, Nb2O5 nanowire networks are self-assembly grown on interdigital electrode patterns by thermal oxidation approach and room temperature hydrogen sensing are also investigated. The inner relationship between microstructural features of the nanowire sizes, orientation, surface and interface etc and the room temperature hydrogen sensing of nanowire network are built. The surface chemical reaction between hydrogen and Nb2O5 nanowires at room temperature are studied combined with theory calculation, in which the bonding features of chemical bonds and its effect on electronic structures will be explored, and then the room temperature hydrogen sensing mechanism of nanowires will be revealed. Nb2O5 nanowire networks decorated by metal Pd/PANI nanoparticles are obtained through in situ chemically oxidative polymerization process. The effect of surface modification on the dissociation, adsorption and diffusion behavior of Nb2O5 nanowires surface hydrogen, and the enhancement physical mechanism of hydrogen sensing response speed of Nb2O5 nanowire networks will be revealed. This proposal will provide theory and experiment basis for developing novel room temperature hydrogen sensing material systems, which have important theory and practical significance for promote the development of hydrogen sensing component with low-cost, miniaturization and high integration.

对低浓度的氢气进行快速、准确的原位探测，具有重要的学术价值和广阔的应用前景。本项目针对目前半导体氧化物材料室温下对氢气检测灵敏度不高和响应速度慢等问题，提出采用热氧化法在叉指电极预图案上自组装Nb2O5纳米线网络并研究其室温氢敏性能，建立纳米线的尺寸、取向、表面与界面等微结构特征与纳米线网络的室温氢气响应灵敏度和响应速度的内在联系；结合理论计算，研究室温下氢与Nb2O5纳米线表面的化学反应，探明化学键的成键特性及其对纳米线电子结构的影响，揭示纳米线的室温氢敏机理；结合原位氧化聚合工艺获得金属Pd/聚苯胺纳米颗粒修饰的Nb2O5纳米线网络，研究表面修饰对Nb2O5纳米线表面氢的解离、吸附和扩散行为的影响，探明提高纳米线网络室温氢气响应速度的物理机制。本项目的顺利实施将为研制新型室温氢气敏感材料体系提供理论和实验依据，对于促进低成本、小型化和高度集成的氢敏元件的发展具有重要的理论和实际意义。

氢气是可再生的清洁能源载体，在诸如冶金、化工、航空航天等领域应用非常广泛，而氢气是一种无色无味的可燃性气体，在生产、储存、运输和使用过程中极易发生泄漏，因此研制出对氢气进行快速、准确探测的氢气传感器显得尤为重要。传统半导体氢气传感器主要存在以下问题：工作温度较高、功耗大、响应速度较慢，对痕量氢气的探测能力低。针对以上问题，本项目采用多种研究方法合成Nb2O5和MoO3纳米棒阵列和纳米线网络，研究纳米材料的合成工艺、生长机理、氢气响应特性和室温敏感机制。首先，采用磁控溅射和光刻工艺在图形化的Si衬底上溅射沉积Nb/Ti叉指图案，研究Nb叉指图案的热氧化工艺，结果显示热氧化产生的热应力易使Nb2O5多晶膜和纳米线从衬底上脱落；通过水热法在金属Nb片上原位生长了[001]取向的六方相Nb2O5纳米棒阵列，基于纳米棒阵列的传感器在浓度为0.2%的氢气环境中，室温下对氢气具有良好的重复性和选择性，响应时间为28s。其次，通过水热法合成了直径100~150nm，长度达1mm的正交相MoO3纳米线；研究表明，不同水热温度下获得MoO3纳米线对浓度为500~1000ppm的H2均有良好的响应，在200℃时获得的纳米线其灵敏度为90%，响应时间为21.4s；对多种还原性气体, 如CO、C2H5OH和丙酮等，均表现出良好的选择性，其对应的灵敏度分别为84%，36%，30.4%和13%；用石墨烯对MoO3纳米线进行修饰，器件的初始电阻从47MΩ降到54kΩ，对1000ppm氢气的响应灵敏度达94%，响应时间为10.5s。此外，采用自组装工艺在疏水衬底上获得MoO3纳米线纸，响应灵敏度和响应速度随氢气浓度的增加而增大，当氢气浓度为1.5%时，响应时间为3 s，基于该纳米线纸的传感器可连续工作5.56年；用Pd量子点修饰MoO3纳米线纸的初始电阻从修饰之前的15MΩ降低至650kΩ，检测限降低到50ppm，相对响应灵敏度为92.3%，且敏感元件具有良好的重复性和选择性。通过对半导体氧化物纳米线生长的工艺优化及其表面修饰的关键技术研究，研制出成本低廉、响应速度快和选择性好的室温氢敏材料，对促进氢气传感器关键技术的发展具有重要意义。