甘氨酸衍生的双介孔掺氮有序介孔炭用于超级电容器和氧气还原

Glycine-derived nitrogen-doped ordered mesoporous carbons with a bimodal mesopore size distribution for supercapacitors and oxygen reduction

  • 摘要: 掺氮多孔炭材料在电化学能量储存和转化方面具有良好的应用前景。可控的氮原子掺杂与孔结构设计对提高其性能起着重要作用。本工作利用无溶剂纳米铸造法,以甘氨酸(Gly)为单一前驱体、以SBA-15为硬模板,制备了掺氮有序介孔炭材料(N-OMCs)。甘氨酸在SBA-15孔道内的限域热解对提高碳产率、氮掺杂量以及构筑双介孔结构非常重要。N-OMCs具有高比表面积(923~1374 m2·g−1)、大孔隙体积(1.32~2.21 cm3·g−1)、双介孔分布(4.8和6.2~20 nm)和高氮含量(3.66%~12.23%)。通过改变Gly/SBA-15的质量比和温度,可以调节材料的结构有序性、粒径、孔隙率和氮掺量。N-OMCs作为电极材料在超级电容器中具有较高性能。最佳样品在0.5 A·g−1时具有298 F·g−1的比电容、高倍率性能(在30 A·g−1时保留70%)与良好的循环稳定性。同时,N-OMCs在电催化氧还原反应(ORR)中也表现出良好性能。最佳样品的起始电位和半波电位分别为0.92和0.83 V,极限电流密度为5.06 mA·cm−2。本工作还讨论了N-OMCs的理化性质与其性能的关系。

     

    Abstract: Nitrogen-doped carbon materials are promising for electrochemical energy storage and conversion. Dopant control and pore engineering play important roles in improving their performance. We have synthesized nitrogen-doped ordered mesoporous carbons (N-OMCs) with a bimodal mesopore size distribution using a solvent-free nanocasting method. The simplest amino acid (glycine, Gly) was used as the only carbon precursor and ordered mesoporous silica SBA-15 as the hard template. The confined pyrolysis of Gly in SBA-15 leads to efficient carbonization, nitrogen doping and an interesting structure. The N-OMCs have high surface areas (923–1374 m2·g−1), large pore volumes (1.32–2.21 cm3·g−1), a bimodal distribution of mesopore sizes (4.8 and 6.2–20 nm) and high nitrogen contents (3.66%–12.23%). The effects of the Gly/SBA-15 mass ratio (1–3) and carbonization temperature (700–1000 °C) on the physicochemical properties of the N-OMCs were studied. When used as electrode materials the N-OMCs have a high performance in supercapacitors. A typical sample has a large specific capacitance of 298 F·g−1, a good rate capability (70% retention at 30 A·g−1) and high stability. The different capacitances and rate capabilities of the N-OMCs are discussed by correlating them with their physicochemical properties. A balance of surface area, degree of graphitization, nitrogen doping, and an open mesoporous structure is essential to achieve the best performance. The N-OMCs also have a good performance in the electrocatalytic oxygen reduction reaction. A typical sample has a high onset of 0.92 V, a high half-wave potential of 0.83 V and a large limiting current density of 5.06 mA·cm−2.

     

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