通过铁掺杂和造孔提高氮掺杂石墨烯/碳纳米管复合物电催化氧还原性能的研究(英文)

Boosting Electrocatalytic Activity of Nitrogen-Doped Graphene/Carbon Nanotube Composite for Oxygen Reduction Reaction

氧还原反应催化剂的性能直接影响着能源转换和存储器件如燃料电池和金属-空气电池的性能.开发低成本、高性能的非铂族金属氧还原催化剂对于这类器件的实际应用和商业化十分重要,因此备受关注.氮掺杂的石墨烯/碳纳米管复合物同时具备碳纳米管的良好导电性能和有利于传质的三维网络结构优点,以及氮掺杂石墨烯的高活性优点,因此有望发展为这类可替代铂族催化剂的氧还原电催化剂之一,但目前其催化性能还需进一步提高.本文研究发现通过在氮掺杂石墨烯/碳纳米管复合物的过程中引入铁元素可以有效提高催化剂的氧还原活性,并且发现通过在热处理和氮掺杂过程中加入二氧化硅纳米颗粒及随后除去二氧化硅,可以在氮掺杂的石墨烯/碳纳米管复合物材料中有效地形成多孔结构.这种多孔结构的形成不仅可以在复合物中引入更多的高活性催化位点,而且有利于暴露更多的催化活性位并促进氧还原反应中的传质过程.结合碳纳米管、石墨烯和多孔结构的三者优点,所制备的多孔氮掺杂碳材料表现出优异的电催化氧还原性能.进一步的实验表明,这类材料还表现出优异的抗甲醇中毒能力和良好的稳定性,因此在性能改进后有望用于燃料电池等能量转换与存储器件.

Developing low-cost catalysts with high electrocatalytic activity for oxygen reduction reaction （ORR） has recently attracted much attention because the sluggish ORR currently limits the performance and commercialization of fuel cells and met- al-air batteries as well. Nitrogen doped carbon materials have been considered as promising candidates for the replacement of high-cost and scarce Pt-based catalysts although their electrocatalytic activity still needs to be much improved. In this work, an im- proved nitrogen-doped graphene/carbon nanotubes composite （N-rGO/CNT） was developed as an efficient ORR electrocatalyst. It was found that the ORR activity of N-rGO/CNT composite could be significantly enhanced by introducing iron in nitrogen-doping process, and further boosted by constructing nanopores in the catalyst for allowing more catalytically active sites accessible and en- hancing mass transfer. Moreover, the electrochemical measurement showed that the improved catalysts exhibited superior tolerance to methanol crossover and good durability, indicating their potential as ORR catalysts for energy conversion and storage applications.