Jiang Shujuan, Li Zhe, Wang Huayu, Wang Yun, Meng Lina, Song Shaoqing
Key Laboratory of Radioactive Geology and Exploration Technology Fundamental Science for National Defense, School of Chemistry, Biology and Materials Science, East China Institute of Technology, Nanchang, Jiangxi Province 330013, P. R. China.
Nanoscale. 2014 Nov 6;6(23):14262-9. doi: 10.1039/c4nr04658g.
Breaking the electron delocalization of sp(2) carbon materials by heteroatom doping is a practical strategy to produce metal-free electrocatalysts of oxygen reduction reaction (ORR) for fuel cells. Whether carbon nanotubes (CNTs) can be efficiently tuned into ORR electrocatalysts only by intrinsic defects rather than heteroatom doping has not been well studied yet in experiment and theory. Here we introduce topological defects of nonhexagon carbon rings into CNTs to break the delocalization of their orbitals and make such type of CNTs to be a high-performance ORR catalyst. The electrochemical tests and theoretical studies indicate that the O₂ chemisorption and the following electrocatalytic activity are promoted by the introduced topological defects and show a strong dependence on the defect amount. Such topological-defect CNTs (TCNTs) have an excellent ORR performance owing to a 3.8-electron-transferring process, ∼4 times higher current density and ∼120 mV more positive peak potential than normally straight CNTs. Moreover, TCNTs show a higher steady-state diffusion current density and much better stability and immunity to crossover effect as compared with commercial Pt/C catalyst. Hence, our results strongly suggest that tuning the surface structure of CNTs with nonhexagon carbon rings is a novel strategy for designing advanced ORR electrocatalysts for fuel cells.
通过杂原子掺杂打破sp(2) 碳材料的电子离域是制备用于燃料电池的氧还原反应（ORR）无金属电催化剂的一种实用策略。碳纳米管（CNTs）是否仅通过固有缺陷而非杂原子掺杂就能有效地调制成ORR电催化剂，在实验和理论上尚未得到充分研究。在此，我们将非六边形碳环的拓扑缺陷引入碳纳米管中，以打破其轨道的离域，使这种类型的碳纳米管成为高性能的ORR催化剂。电化学测试和理论研究表明，引入的拓扑缺陷促进了O₂化学吸附及随后的电催化活性，且对缺陷量有强烈依赖性。这种拓扑缺陷碳纳米管（TCNTs）由于具有3.8电子转移过程，具有优异的ORR性能，与通常的直碳纳米管相比，电流密度高约4倍，峰值电位更正约120 mV。此外，与商业Pt/C催化剂相比，TCNTs表现出更高的稳态扩散电流密度以及更好的稳定性和抗交叉效应能力。因此，我们的结果有力地表明，用非六边形碳环调节碳纳米管的表面结构是设计用于燃料电池的先进ORR电催化剂的一种新策略。
