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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.
The performance of the oxygen reduction reaction catalyst directly affects the performance of energy conversion and storage devices such as fuel cells and metal-air cells. The development of low-cost, high-performance non-platinum group metal oxygen reduction catalysts is very practical and commercial for such devices Therefore, the nitrogen-doped graphene / carbon nanotube composite possesses both the excellent conductivity of the carbon nanotubes and the advantages of the three-dimensional network structure that is conducive to mass transfer as well as the high activity advantages of the nitrogen-doped graphene, Therefore, it is expected to develop into one of such oxygen reduction electrocatalysts that can replace the platinum group catalyst, but its catalytic performance needs to be further improved at present.This study found that by introducing nitrogen into the graphene / carbon nanotube composite during nitrogen doping Element can effectively increase the oxygen reduction activity of the catalyst and found that by adding silica nanoparticles during heat treatment and nitrogen doping and then removing the silica, it is found that in the nitrogen-doped graphene / carbon nanotube composite material Effectively forming a porous structure that is not only capable of introducing more highly active catalytic sites in the complex, Which is conducive to exposing more catalytic active sites and promoting the mass transfer in the oxygen reduction reaction.Combining the advantages of carbon nanotubes, graphene and porous structure, the prepared porous nitrogen-doped carbon material exhibits excellent electrocatalysis Oxygen reduction performance.Further experiments show that these materials also show excellent resistance to methanol poisoning and good stability, so after the performance improvement is expected to be used for fuel cell and other energy conversion and storage devices.