Abstract Nitrogen-doped mesoporous graphene hydrogel (MGHG) enjoys many unique characteristics for use as an efficient energy storage electrode material. Herein, a green one-pot hydrothermal synthesis strategy was employed to synthesize highly hydrophilic nitrogen-doped mesoporous graphene hydrogel. The morphological, structural, and compositional analyses were performed using FESEM, XRD, and XPS techniques. The as-prepared MGHG exhibits high wettability (contact angle = 58.9o), high surface area (318.226 m2/g), and an unprecedented nitrogen doping content of 2.95%. The fabricated MGHG was evaluated as a supercapacitor material in 1 M aqueous K2SO4 electrolyte, revealing a maximum specific capacitance of 595.7 F.g−1 with a low equivalent series resistance (0.1664 Ω) that is ascribed to the high porosity, high surface area, and the available nitrogen redox active sites. To further elucidate the electrochemical performance of MGHG, a symmetric supercapacitor device was assembled using MGHM as negative and positive electrodes. The fabricated device shows a maximum specific energy of 30 Wh kg−1 corresponding to a specific power 1000 W kg−1. The density functional theory (DFT) computations were utilized to better understand the high performance of the assembled devices. These superior results demonstrate the excellent performance of MGHG as a potential material for highly-performing supercapacitor devices with a potential window of 2.2 V.

中文翻译：

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通过过量氮掺杂提高石墨烯水凝胶的循环稳定性和超级电容性能：实验和 DFT 见解

摘要 掺氮介孔石墨烯水凝胶（MGHG）作为一种高效的储能电极材料具有许多独特的特性。在此，采用绿色一锅水热合成策略合成高亲水性氮掺杂介孔石墨烯水凝胶。使用 FESEM、XRD 和 XPS 技术进行形态、结构和成分分析。所制备的 MGHG 具有高润湿性（接触角 = 58.9o）、高表面积（318.226 m2/g）和前所未有的 2.95% 的氮掺杂含量。制造的 MGHG 被评估为 1 M K2SO4 水溶液中的超级电容器材料，显示最大比电容为 595.7 Fg-1，具有低等效串联电阻 (0.1664 Ω)，这归因于高孔隙率、高表面积，和可用的氮氧化还原活性位点。为了进一步阐明MGHG的电化学性能，使用MGHM作为负极和正极组装了对称超级电容器装置。制造的装置显示出最大比能量为 30 Wh kg-1，对应于 1000 W kg-1 的比功率。密度泛函理论 (DFT) 计算被用来更好地理解组装设备的高性能。这些优异的结果证明了 MGHG 作为具有 2.2 V 电位窗口的高性能超级电容器器件的潜在材料的优异性能。制造的装置显示出最大比能量为 30 Wh kg-1，对应于 1000 W kg-1 的比功率。密度泛函理论 (DFT) 计算被用来更好地理解组装设备的高性能。这些优异的结果证明了 MGHG 作为具有 2.2 V 电位窗口的高性能超级电容器器件的潜在材料的优异性能。制造的装置显示出最大比能量为 30 Wh kg-1，对应于 1000 W kg-1 的比功率。密度泛函理论 (DFT) 计算被用来更好地理解组装设备的高性能。这些优异的结果证明了 MGHG 作为具有 2.2 V 电位窗口的高性能超级电容器器件的潜在材料的优异性能。