2D metal–organic framework derived ultra-thin nitrogen-doped oxygen rich porous carbon nanosheets for zinc-ion hybrid supercapacitors

Abstract

Zinc-ion hybrid supercapacitors (ZIHSCs) have attracted immense interest owing to their considerable energy density. However, the sluggish Zn²⁺ transfer kinetics on the cathode materials of ZIHSCs result in poor rate-capability and low capacity. Herein, we employ a two dimensional (2D) metal–organic framework (MOF) nanosheet precursor to fabricate ultra-thin N-doped oxygen-rich porous carbon nanosheets (A-NOCNSs). Owing to the merits of the 2D MOF precursor, the as-prepared A-NOCNSs have an atomically thin thickness of only 2.5 nm, a high surface area, and a hierarchical porous structure with a microporous pore domain, which provide abundant surface active sites, fast ion diffusion channels, and efficient charge transport paths. Moreover, the uniform doping of N and rich O atoms provides extra redox capacitance, as well as super-hydrophilic properties. Consequently, the ZIHSC based on the A-NOCNSs delivers an ultrahigh specific capacity of 176.48 mA h g⁻¹ at 0.2 A g⁻¹, exceptional energy and power densities (162.88 W h kg⁻¹ and 28.43 kW kg⁻¹, respectively), and long-term cycling stability (90.23% after 20 000 cycles at 10 A g⁻¹). The A-NOCNSs demonstrate great potential for advanced ZIHSC applications and may initiate the booming of the research of high-performance 2D carbon cathode materials using MOF precursors in the future.