Three-dimensional nitrogen-rich porous carbon materials (NPCs), with advantageously tuned physicochemical properties through nitrogen functionalities, have become the research hotspot of energy storage. As electrodes for supercapacitors, NPCs fabricated via a facile strategy are highly desirable to improve the limited performance of N-doped species and obtain high specific capacitance. Herein, a graphene/nitrogen-rich carbon foam with a 3D hierarchically porous architecture has been achieved through assembling graphene oxide sheets into melamine foam. The obtained foam with meso- and micro-pores, nitrogen-enriched content (11.6 at%), and a large surface area (943.7 m² g⁻¹) delivers enhanced energy storage capabilities of 324, 229, and 196 F g⁻¹ at current densities of 0.1, 1, and 10 A g⁻¹ in a 6 mol L⁻¹ KOH electrolyte, respectively. Moreover, the as-prepared material shows an appreciable capacitance of up to 213 F g⁻¹ at 0.1 A g⁻¹, along with excellent cycling stability (99% retention after 10 000 cycles in a PVA/KOH gel electrolyte) in the related fabricated symmetric solid-state supercapacitors.

中文翻译：

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一种用于高性能超级电容器的分层多孔石墨烯/富氮碳泡沫的简单策略

三维富氮多孔碳材料（NPC）具有通过氮官能团有利地调节理化特性的特性，已成为储能的研究热点。作为用于超级电容器的电极，非常需要通过简便的策略制造的NPC，以改善N掺杂物质的有限性能并获得高比电容。在此，通过将氧化石墨烯片组装成三聚氰胺泡沫体，已经获得了具有3D分级多孔结构的石墨烯/富氮碳泡沫。所获得的具有中孔和微孔，富氮含量（11.6 at％）和大表面积（943.7 m ² g ^-1）的泡沫可提供增强的324、229和196 F g ^-1能量存储能力在6 mol L ^-1 KOH电解质中的电流密度分别为0.1、1和10 A g ^-1。此外，所制备的材料在相关材料中显示出在0.1 A g ^-1时高达213 F g ^-1的可观电容，并具有出色的循环稳定性（在PVA / KOH凝胶电解质中进行10 000次循环后99％的保留率）制成的对称固态超级电容器。