Nano assembly of N-doped graphene quantum dots anchored Fe3O4/halloysite nanotubes for high performance supercapacitor

Abstract

The development of robust and low cost electrode materials with superior electrochemical properties has been a subject of focus on energy storage devices. Herein, the development of N-doped graphene quantum dots (N-GQDs) deposited on Fe3O4-halloysite nanotubes (Fe3O4-HNTs) as active anode materials has been established for supercapacitor applications. The Fe3O4 nanoparticles synthesised by coprecipitation have been in-situ deposited on HNT surfaces following by the coating of (3-aminopropyl)-triexthoxysilane to anchor 4-10 nm N-GQDs via the formation of amide linkage. The N-GQD@Fe3O4-HNTs exhibits a high specific capacitance of 418 F g(-1) and maintains good rate capability in neutral electrolyte solutions. In addition, the anode materials show excellent electrochemical performance with energy and power densities of 10.4-29 W h kg(-1) and 0.25-5.2 kW kg(-1), respectively. Such excellent electrochemical features can be attributed to the synergistic contribution from individual components. The Fe3O4-HNTs provide 1-dimensional matrix to shorten the diffusion path of electrons and electrolyte ions as well as to absorb the mechanical stress during cycling along with excess sites for charge storage, while N-GQDs offer abundantly accessible electroactive sites for rapid electrons and electrolyte ions transport as well as enhance electrical conductivity of Fe3O4-HNTs. Results obtained in this study clearly demonstrate that metal oxide-HNTs are promising support to anchor N-GQDs nanomaterials as the high performance anode materials for next generation of energy storage devices with high energy and power densities. (C) 2017 Elsevier Ltd. All rights reserved.