Carbon-incorporated Fe3O4 nanoflakes: high-performance faradaic materials for hybrid capacitive deionization and supercapacitors

Here, we introduce a new strategy using urea for the synthesis of carbon-incorporated 2D Fe3O4 (2D-Fe3O4/C) nanoflakes under solvothermal conditions with the following pyrolysis process under an inert atmosphere. Thanks to the structural advantages of 2D-Fe3O4/C, including 2D flakes providing a larger accessible surface area and exposing more active sites, as well as carbon incorporation promoting electrical conductivity for faster charge transfer, the 2D-Fe3O4/C displays a high specific capacitance of 386 F g(-1) at 1 A g(-1) in a three-electrode system. More importantly, when further assembled into a hybrid supercapacitor with pre-synthesized NiCo-layered double hydroxides as positive electrodes, the assembled supercapacitor device delivers a high-energy density of 32.5 W h kg(-1) at 400 W kg(-1) and little capacitance loss with bending angles ranging from 0 degrees to 180 degrees. As another capacitive application in desalination, 2D-Fe3O4/C also shows a high desalination capacity of 28.5 mg g(-1) over 7.5 min, which suggests a very high mean desalination rate of 3.8 mg g(-1) min(-1). Our results not only highlight the significance of 2D metal oxide nanosheets/nanoflakes, but also hold great potential for high-performance capacitive applications in supercapacitors and desalination.

Automated summary

A new synthesis strategy using urea to create carbon-incorporated 2D Fe3O4 nanoflakes under solvothermal conditions has been developed, showing high specific capacitance and energy density. The structural advantages and carbon incorporation enable faster charge transfer, making it suitable for high-performance capacitive applications in supercapacitors and desalination.