氮掺杂石墨烯的制备及其电催化氧气还原性能

Synthesis of nitrogen-doped graphene and its catalytic activity for the oxygen reduction reaction in fuel cells

  • 摘要: 通过改良Hummers法制备氧化石墨(Graphite oxide, GO),采用爆炸辅助还原法将GO还原剥离并原位掺杂得到氮掺杂石墨烯(Nitrogen-doped graphene,N-RGO)。采用TEM、SEM、FI-IR、XPS、XRD及Raman等分析手段对N-RGO的形貌、组成以及结构进行了表征,利用旋转环盘电极技术测试了其电催化氧气还原活性。TEM和SEM结果表明,爆炸条件下GO被很好地剥离开来,得到只有几层厚度的石墨烯;FI-IR及XPS结果表明, GO中大部分含氧官能团被脱除,C/O原子比达到26.2,是目前所得GO还原程度非常高的方法之一,且氮元素成功掺杂进石墨烯晶格中,掺杂氮的原子质量分数约为2.11%;电化学测试结果显示,氧气还原的极限扩散电流由非氮掺杂石墨烯(Reduced graphene oxide,RGO)的0.24mA提高到N-RGO的0.49mA,尽管爆炸辅助还原得到的RGO对氧气还原也显示出较好的催化活性,但掺杂之后的N-RGO具有更高的催化活性。

     

    Abstract: Graphene was synthesized by the detonation-assisted reduction of graphite oxide (GO) prepared by the modified Hummers method. Nitrogen-doped reduced GO(N-RGO)was obtained through an in-situ nitrogen-doping during detonation. The morphology, elemental composition and structure of the N-RGO were characterized by TEM, SEM, IR, XPS, XRD and Raman spectroscopy. The catalytic activity of the N-RGO as a fuel cell electrode for the oxygen reduction reaction (ORR) was investigated by a rotating ring disk electrode technique. Results showed that the GO was exfoliated and reduced to few layer graphene by the detonation. The oxygen-containing species of GO were reduced and the C/O molar ratio was increased to 26.2, which is much higher than for RGO. Nitrogen, as high as 2.11 at%, was incorporated into the graphene structure. The diffusion-limited current for ORR increased from 0.24 mA for RGO to 0.49 mA for N-RGO, indicating a higher catalytic activity of N-RGO for ORR than that of RGO.

     

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