Hydrogels with unique three-dimensional (3D) macroscopic porous architectures are attractive electrode materials for supercapacitors because of their superior electrolyte permeabilities and rapid electron/ion transports. In this letter, a cylindrical-type 3D macroscopic graphene/MXene-based hydrogel (GMH) is prepared by self-assembling laminar-structured graphene oxide (GO) and MXene (Ti3C2) nanosheets via a facile one-step hydrothermal method under the existence of ammonia water and hydrazine hydrate. GO is found to self-converge into a 3D macroscopic porous graphene framework during the hydrothermal process, while Ti3C2 nanosheets are able to prevent the graphene nanosheets from self-restacking. The as-prepared GMH shows a larger specific surface area of 161.1 m2 g−1 and a higher pore volume of 0.5 cm3 g−1 in comparison with the pure graphene hydrogel. A symmetric supercapacitor utilizing GMH as electrodes exhibits high energy densities of 9.3 Wh kg−1 and 5.7 Wh kg−1 at different power densities of 500 W kg−1 and 5000 W kg−1, respectively, as well as an outstanding long-term cycle stability with no loss in capacitance in excess of 10 000 continuous charge–discharge cycles. The strategy of preparation of a 3D macroscopic GMH is expected to realize promising high-performance hydrogel electrodes based on graphene and MXene for electrochemical energy storages.

中文翻译：

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自组装三维宏观石墨烯/MXene基水凝胶作为超级电容器的电极

具有独特的三维 (3D) 宏观多孔结构的水凝胶由于其优异的电解质渗透性和快速的电子/离子传输，是极具吸引力的超级电容器电极材料。在这封信中，圆柱型 3D 宏观石墨烯/MXene 基水凝胶 (GMH) 是通过自组装层状结构氧化石墨烯 (GO) 和 MXene (Ti3C2) 纳米片通过简单的一步水热方法在存在下制备的氨水和水合肼。发现 GO 在水热过程中自会聚成 3D 宏观多孔石墨烯框架，而 Ti3C2 纳米片能够防止石墨烯纳米片自重堆叠。所制备的 GMH 显示出更大的比表面积 161.1 m2 g-1 和更高的孔体积 0。5 cm3 g-1 与纯石墨烯水凝胶相比。使用 GMH 作为电极的对称超级电容器在 500 W kg-1 和 5000 W kg-1 的不同功率密度下分别表现出 9.3 Wh kg-1 和 5.7 Wh kg-1 的高能量密度，以及出色的长期循环稳定性，在超过 10 000 次连续充放电循环后电容没有损失。制备 3D 宏观 GMH 的策略有望实现基于石墨烯和 MXene 的用于电化学储能的有前途的高性能水凝胶电极。以及出色的长期循环稳定性，超过 10 000 次连续充放电循环后电容不会损失。制备 3D 宏观 GMH 的策略有望实现基于石墨烯和 MXene 的用于电化学储能的有前途的高性能水凝胶电极。以及出色的长期循环稳定性，超过 10 000 次连续充放电循环后电容不会损失。制备 3D 宏观 GMH 的策略有望实现基于石墨烯和 MXene 的用于电化学储能的有前途的高性能水凝胶电极。