基于NH3敏感的NiO纳米锥构筑研究

The rare of gas-sensing materials, which own high sensitivity, stability and selectivity, is the key issue restricting the development of gas-sensing technology. At present, the research of high-performance gas-sensing materials mainly focus on the development of nanomaterials, however, the research of constructing gas-sensing materials for the comprehensive utilization of traditional materials and nanomaterials is still inadequate. This project intends to construct NiO nanocones that are sensitive to NH3 via the experimental study and theoretical analysis. The main contents of the project include: the relation of coarsening characteristics of traditional Ni base on the surface and nucleation sites of crystals, analyzing the impact of the complexation and decomposition of composite precursor on the absorption and release behavior of Ni2+, the relation of crystal growth rate and characteristic of self-assembly on nanocones, the dynamic distribution of Ni/O atoms and transfer behavior of amorphous NiO, revealing the nucleation, self-assembly and in-situ oxidation mechanism of nanocones during the process of construction; combined with the composite gas sensitive effect of traditional materials and nanomaterials, analyzing the adsorption characteristics of NH3 molecule on the surface of nanocones and the transmission behavior of carriers, in order to find the effective constructing method of NiO nanocones that are sensitive to NH3. The research results could provide the theoretical basis for the design and construction of a new type of gas-sensing materials, improving the comprehensive gas-sensing performance of micro gas sensor, and the precision detection of gas molecules.

同时具备高灵敏度、稳定性和选择性的气敏材料缺乏是制约气敏传感技术发展的关键。目前，高性能气敏材料的研究主要侧重于纳米材料的开发，而对于综合利用传统材料和纳米材料的优势构筑气敏材料的研究尚显不足。本项目拟以NH3敏感的NiO纳米锥构筑为研究对象，采用实验研究和理论分析有机结合的方法，研究传统材料Ni基底表面的粗化特征与质点形核位置的关系，分析复合前驱体的络合与分解对Ni2+吸收与释放行为的影响，明晰晶面生长速率与纳米锥自组装特征的关联，阐明Ni/O原子的动态分布及无定形NiO的转移行为，从而揭示纳米锥构筑过程中基底形核、自组装和原位氧化机制；结合传统材料和纳米材料的复合气敏效应，分析NH3分子在纳米锥表面的吸附特征及载流子的传输行为，以期提出基于NH3敏感的NiO纳米锥的有效构筑方法。项目研究结果可为新型气敏材料的设计与构筑、微型气敏传感器综合性能的提升及气体分子的精确检测提供理论基础。

在传统材料表面构建纳米晶超结构，既能克服传统材料比表面积小的不足，又可避免纳米晶超结构的搭接缺陷，是同时提升灵敏度、稳定性和选择性的有效途径。项目创新性地利用高压液相体系的化学还原组装特征，实现了球形粒子-纳米锥协同构建NiO榴莲状微结构；采用两步互换电极电沉积技术联合高温氧化法，在传统箔基底定向吸附镍离子并还原形核组装NiO纳米锥超结构；基于构建的PPTA纤维表面微凹凸特征，利用敏化活化及液相化学沉积原理，在柔性PPTA纤维表面分层沉积了Cu/Ni复合金属层，并通过步进式原位氧化途径构筑了同型异质结气敏复合材料。NiO纳米锥组装的榴莲状微结构因对拥有孤对电子的氨分子具有快速的选择性物理吸附，故在50ppm氨气中电导变化率超过40%，且响应和恢复时间仅需6.3s和17.2s，并对氨气具有出色的选择性和稳定性。基于放电效应和螺旋位错诱导生长构建的NiO箔基底/纳米锥超结构对不同浓度的氨气表现出优异的敏感性、快速的响应/恢复特性、良好的稳定性和在各种有毒、可燃、易爆气体中独特的氨气选择性，其归因于箔基底电子传输的稳定性和纳米锥超比表面积的优势集成。创制的NiO@CuO-PPTA纤维复合柔性气敏材料不仅具有优异的柔韧性和热稳定性，即450℃环境中质量变化率小于0.03，而且拥有室温氨气的ppb检测限；优异的综合气敏性能源于层状同型异质结建立的势垒差，提升了载流子穿越内建电场的传输速率。项目研究结果为新型气敏材料的设计与构筑、微型气敏传感器综合性能的提升及气体分子的精确检测提供了理论与技术基础。