模板法构筑异质结构薄壁碳纳米管多功能电催化剂研究

In this project, thin-wall carbon nanotubes (CNTs) will be fabricated by using large-pore porous alumina templates and one-step low-temperature chemical vapor deposition. Then, by combining multiple-step procedures, such as high-temperature annealing, nitrogen doping and plasma treatment, this project will further fabricate hierarchically structured nitrogen-doped CNTs, where inner walls are hydrophilic, and inside, inner surface, and outer surface of walls are incorporated with different transition metal nitrides. Also, controlled tuning of type and concentration of transition metal nitrides at each position of the CNT walls will be achieved. By combing theoretical computation, this project will study the dependence of (oxygen reduction/oxygen evolution/hydrogen evolution reactions) electrocatalytic activities of these hierarchically structured CNTs on their inner wall hydrophilization, wall thickness, nitrogen concentration, type and concentration of the transition metal nitrides as well as the position where the transition metal nitrides are incorporated with CNT walls. Then, this project will reveal the electrocatalytic active sites of these hierarchically structured CNTs, search for their best electrocatalytic performance, and clarify their electrocatalytic mechanisms. Finally, for hierarchically structured CNTs which have high electrocatalytic activities, this project will apply them to electrode materials of energy devices, such as fuel cells, and rechargeable zinc-air batteries. This project will benefit the achievement of cheap, highly active, and highly durable multifunctional electrocatalysts, and will provide theoretical foundation for the design and synthesis of high-performance electrocatalysts.

本项目拟利用大孔径的多孔氧化铝模板和低温化学气相沉积来制备薄管壁的碳纳米管。然后，结合高温退火、氮掺杂、等离子体处理等多步操作，制备管壁内表面亲水、管壁内部以及内外表面分别结合不同种类过渡金属氮化物的氮掺杂异质结构碳纳米管，并实现其管壁每一处过渡金属氮化物的种类和含量的可控调节。本项目拟结合理论计算研究管壁内表面亲水性、管壁厚度、氮掺杂量、过渡金属氮化物种类、含量以及与管壁的结合位置对异质结构碳纳米管多功能（氧还原/氧析出/氢析出）电催化活性的影响，从而揭露其电催化活性位点，探索其最佳的电催化性能，并阐明其电催化机理。最后，本项目拟利用多功能高电催化活性的异质结构碳纳米管作为电极材料应用于燃料电池、可再充锌-空气电池等能源器件。本项目的实施，有利于获得廉价、高活性、高稳定性的多功能电催化剂，并为设计和制备高性能的电催化剂提供理论依据。

本项目通过在陶瓷舟内部放置硝酸铜，然后采用化学气相沉积法，实现了多孔、疏水、高纯度碳纳米纤维网络在陶瓷舟外表面以及各种陶瓷废弃物表面的可控生长。然后，通过对碳纳米纤维网络进行等离子体处理或者氨气退火，并且合理控制实验参数，制备了正反两面带有不同润湿性的Janus碳纳米纤维网络。所得Janus碳纳米纤维网络表面的疏水性区域可以实现滴水导致的可见/不可见可逆性转变，或者同时去除水表面的油类和溶解在水中的染料。此外，通过在铝片表面生长碳纳米纤维薄膜，然后将铝片腐蚀掉，得到了自支撑的碳纳米纤维薄膜。这种碳纳米纤维薄膜具有良好的疏水性和力学弹性，可以实现对有机溶剂或者油类的高容量吸附。另外，通过以松木碳粉做基底，玉米秸秆作为碳源，实现了碳纳米纤维的全生物质合成。然后，通过对碳纳米纤维进行氨气退火使其具有氮掺杂和亲水/水下疏油性，再通过真空过滤将其制成滤膜，我们实现了水包原油乳液和染料的同时高效分离。除了用于滤膜之外，这种氮掺杂碳纳米纤维在修饰氧化钴以后，还具有比商用氧化铱更高的氧析出反应电催化活性。本项目还通过对石墨和硝酸铁进行球磨，然后再对石墨进行氨气退火，得到了氮化铁/氮掺杂石墨烯复合结构。所得复合结构对氧还原反应和氧析出反应同时具有高电催化活性。利用这种复合结构组装的锌空电池表现出了高功率密度和优良的循环性能。本项目的研究结果可以为低成本、高性能的湿敏防伪产品和电化学催化剂的设计与制备提供新的思路。