负载高浓度单原子金属碳纳米管的制备及催化性能研究

Recently, it has been found that single atom catalysts (SACs) show excellent efficiency, activity and selectivity. With increased concentration of single atoms, SACs intend to aggregate and form clusters or particles, which degrades the catalytic efficiency dramatically. Currently, the loadings of SACs are usually lower than 3 wt %, and the limited amount of active sites retrains their overall catalysis performance. To address these problems, we propose a novel " C-N self-confinement" method, by which metal single atoms are firmly anchored on a N-doped carbon nanotube structure, and the loadings of single metal atoms can be as high as 10 wt.%. The method of preparing high-concentration single atom metal -loaded carbon nanotubes will be established. The way that metal single atoms be trapped in carbon nanotubes will be studied. The catalysis performance and mechanism of the high-concentration single atom metal -laoded carbon nanotubes toward oxygen reduction, oxygen evolution, and carbon dioxide reduction reactions will be investigated. This project will pave the way for controlled synthesis and catalysis application of high-concentration single atom metal-loaded carbon nanotubes.

近期研究发现单原子金属催化剂具有超高的效率、活性及优异的选择性。但当浓度较高时，高活性的单原子金属易发生团聚而形成颗粒。目前，单原子金属的负载量通常低于3wt%，有限的活性位点数量限制了其催化性能的显著提升。针对以上问题，本申请提出采用一种 “碳氮限域”方法，将单原子金属固定在氮掺杂碳纳米管中，利用碳、氮及单原子金属形成的自稳定结构使得单原子金属的负载量显著提高（>10wt.%）；将建立负载高浓度单原子金属碳纳米管的制备方法；揭示单原子金属在碳纳米管中的锚固机制；研究负载高浓度单原子金属碳纳米管在氧还原、氧析出、二氧化碳还原等反应中的催化性能，优化单原子的组分及负载量，并揭示其催化机制。通过本项目研究，为负载高浓度金属单原子碳纳米管的可控制备及催化应用奠定科学基础。

单原子金属作为一种高活性电催化剂在燃料电池、锌空电池及CO2还原等领域具有良好应用前景。但浓度较高的金属单原子易发生团聚，限制了其负载量及催化性能的进一步提高。基于此，本项目建立了一步法制备出负载镍单原子达15 wt %的碳纳米管；以“种子法”在不同二维材料上制备浓度可调、成分可控的单原子金属，发现其具有优异的CO2还原性能；发展了“氟化抓取Fe单原子-氨化锚定Fe-Nx活性位点”方法制备出单壁碳纳米管自支撑电催化薄膜电极，并利用其组装性能优于贵金属基催化剂的柔性全固态锌空电池；通过在交叉缠绕成海绵的碳微米管表面枝接Fe-ZIF-8，批量制备出高浓度单原子铁锚定且具有优异氧还原性能碳微米管宏观体。实验研究结合理论模拟揭示了高浓度单原子金属催化剂结构与其电催化性能之间的关系，为非贵金属基电化学能量存储与转换器件的研发与应用提供借鉴。