金属与氮掺杂对碳纳米管阵列氢传感效应影响的机理研究

Low-pressure hydrogen sensing is an important issue in many fields, such as oil and gas transmission, space technology and vacuum measurement. Metal and nitrogen-doped carbon nanotube arrays can be widely used for gas sensing. However, the current hydrogen sensing mechanism for field emission is not clear yet. For the first time, the controllable preparation technology, the mechanism of field emission hydrogen sensing and the structure characteristics of the metal and nitrogen-doped carbon nanotube arrays are first investigated. In this project: (1) we firstly prepare the high purity nitrogen-doped carbon nanotube arrays using ZnO template, then the controlled preparation of metal and nitrogen-doped carbon nanotube arrays and the sensing mechanism will be investigated from the field emission and the structural characteristic; (2) based on the first principle density functional theory, the key featural parameters of metal and nitrogen-doped carbon nanotube, including the energy band, density of states, work function, adsorption energy and other parameters, will be caculated and the electron transport performance during field emission will be investigated; (3) through the study of doped metal in inner tube and bimetal co-doped NCNT, the approaches of improving the sensitivity, including the temperature characteristics, the concentration characteristics and response recovery features of hydrogen sensing, will be studied. The investigation will lay the foundation for its applications in field emission,energy and catalysis.

低压氢传感在油气传输、空间技术及真空计量等领域有重要作用，金属与氮掺杂碳纳米管阵列可广泛用于气体传感，但目前其场发射氢传感机理仍不清晰。本项目首次立项对金属与氮掺杂碳纳米管（NCNT）可控制备的技术工艺、场发射氢传感机理及其结构特征进行研究，具体内容包括：（1）先采用氧化锌模板制备高纯NCNT，再采用电泳法、蒸镀法和化学法，研究金属与氮掺杂碳纳米管阵列的可控制备，实验研究场发射氢传感机理及掺杂碳纳米管的结构特征；（2）基于密度泛函第一性原理，通过研究氢吸附金属与氮掺杂碳纳米管后，其能带、态密度、功函数、吸附能等参数的改变对其场发射时电子输运性能的影响，来研究其氢传感机理；（3）深入研究氢传感机理，研究管内掺杂金属、双金属共掺NCNT，来探索提高氢气传感的温度、浓度及响应恢复等特性的技术途径。研究也将为为金属与氮掺杂碳纳米管阵列在场发射、能源和催化领域的应用奠定基础。

场发射低压氢传感技术可应用于复杂气体环境及真空系统中氢气的检测，由于器件微型、简易等优势，在真空电子器件、真空系统检测、航空航天等领域有重要的应用前景。金属与氮掺杂碳纳米管可广泛应用于氢气传感，但低压氢传感研究较少且低压氢传感机理仍不清晰。本项目在金属和氮掺杂CNT材料制备、场发射低压氢传感机理等方面取得了实验和理论方面的一些成果。研究结果表明：金属（Fe,Co,Ni,Ag和Pt）掺杂CNT后能够有效促进氢分子的解离，使得氢原子吸附在掺杂CNT表面，导致CNT有效功函数的下降，从而产生了氢传感效应。当氮掺杂CNT后，吡咯氮吸附氢原子后使得CNT有效功函数下降，而石墨氮和吡啶氮吸附氢原子后，CNT有效功函数则变大。金属与氮共掺杂CNT后，CNT功函数下降更快，氢传感效应更明显。金属和氮共掺杂CNT吸附氢原子后，在压力范围为10−4-10−7 Pa条件下，1分钟内其传感电流增幅可达到126%，具有较好的应用价值。研究也将为金属与氮掺杂CNT在场发射、场发射低压氢传感、能源电池等多领域应用提供了较好的理论基础。