The energy and environmental crises have forced us to search for a new green energy source and develop energy storage and environmental restoration technologies. Fabrication of carbon functional materials derived from coal has attracted increasing attention in the energy storage and gas adsorption fields. In this study, an N, O-co-doped porous carbon/carbon nanotube composite was prepared by functionalizing coal-based porous carbon with carbon nanotubes (CNTs) and ionic liquid via annealing. The resulting material not only inherited the morphology of CNTs and porous carbon, but also developed a three dimensional (3D) hierarchical porous structure with numerous heteroatom groups. The N, O co-doped porous carbon/CNT composite (N, O-PC-CNTs) showed a surface area of 2164 m² g⁻¹, and a high level of N/O dopants (8.0 and 3.0 at%, respectively). Benefiting from such merits, N, O-PC-CNTs exhibited a rather high specific capacitance of 287 F g⁻¹ at a current density of 0.2 A g⁻¹ and a high rate capability (70% and 64% capacitance retention at 10 and 50 A g⁻¹, respectively) in a three electrode system. Furthermore, an N, O-PC-CNT symmetrical supercapacitor showed a high cycling stability with 95% capacitance retention after 20 000 cycles at 20 A g⁻¹ and an energy density of 4.5 W h kg⁻¹ at a power density of 12.5 kW kg⁻¹ in 6 mol L⁻¹ KOH electrolyte. As a CO₂ adsorbent, N, O-PC-CNTs exhibited a high CO₂ uptake of 5.7 and 3.7 mmol g⁻¹ at 1 bar at 273 and 298 K, respectively. Moreover, N, O-PC-CNTs showed cycling stability with 94% retention of the initial CO₂ adsorption capacity at 298 K over 10 cycles. This report introduces a strategy to design a coal based porous carbon composite for use in efficient supercapacitor electrodes and CO₂ adsorbents.

中文翻译：

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用于超级电容器和 CO2 捕集的煤衍生的分层结构 N、O 共掺杂多孔碳/碳纳米管复合材料

能源和环境危机迫使我们寻找新的绿色能源，开发储能和环境修复技术。以煤为原料的碳功能材料的制备在储能和气体吸附领域引起了越来越多的关注。在这项研究中，通过退火使碳纳米管（CNT）和离子液体功能化煤基多孔碳，制备了N，O-共掺杂的多孔碳/碳纳米管复合材料。所得材料不仅继承了碳纳米管和多孔碳的形态，而且还形成了具有大量杂原子基团的三维（3D）分级多孔结构。N，O共掺杂多孔碳/CNT复合材料（N，O-PC-CNTs）的表面积为2164 m ² g^-1和高水平的 N/O 掺杂剂（分别为 8.0 和 3.0 at%）。得益于这些优点，N, O-PC-CNTs 在0.2 A g -1 的电流密度下^表现出相当高的比电容 287 F g ^-1和高倍率性能（70% 和 64% 的电容保持率在 10 和50 A g ^-1，分别）在三电极系统中。此外，N、O-PC-CNT 对称超级电容器表现出高循环稳定性，在 20 A g ^-1下 20 000 次循环后具有 95% 的电容保持率，在 12.5 kW 的功率密度下能量密度为 4.5 Wh kg ^-1 kg ^-1在 6 mol L ^-1 KOH 电解液中。作为 CO ₂吸附剂、N、O-PC-CNT在 273 和 298 K 的 1 bar 下分别表现出 5.7 和 3.7 mmol g ^-1的高 CO ₂吸收。此外，N，O-PC-CNTs表现出循环稳定性，在298 K下10个循环后初始CO ₂吸附容量保持94%。本报告介绍了一种设计用于高效超级电容器电极和 CO ₂吸附剂的煤基多孔碳复合材料的策略。