Fabrication and electrochemical behavior of halloysite/ graphene-polyaniline three-dimensional hybrid aerogel loaded with iron oxide

• Halloysite nanotubes were fixed on the surface of graphene sheets or embedded between graphene nanosheets, forming a three-dimensional network structure, which reduced the agglomeration between graphene sheets. • The hybrid of halloysite nanotube and graphene sheet increased the graphene's specific surface area and realized a three-dimensional network porous structure. • The synergistic effect of iron oxide and polyaniline made the composites have larger capacitance, the capacitance reaches 557.6 Fg −1 . • After 1000 cycles, the specific capacitance of composites remained 81%. Great progress had been made in the synthesis and application of graphene, graphene oxide (GO) aerogels, and reduced graphene oxide (rGO). However, most of the reported graphene hybrid aerogels reduced the mechanical properties of the obtained materials because of their wide pore size distribution, which limited the recycling of aerogels. Therefore, it was urgent to prepare graphene hybrid aerogels with uniform mesopores or micropores to enhance the structural stability of aerogels. Meanwhile, the mechanical and electrical properties of graphene hybrid aerogels could be further improved. In this paper, halloysite/graphene-polyaniline three-dimensional hybrid aerogel loaded with Fe 3 O 4 (HGA-PANI) was fabricated. The microstructure, mechanical properties, and electrochemical properties of HGA-PANI were characterized by scanning electron microscope (SEM), X-ray Photoelectron Spectroscopy (XPS), N 2 adsorption-desorption tests, universal material testing machine, electrochemical workstation, and so on. Halloysite nanotubes (HNT) were fixed on the surface of graphene sheets or intercalated between graphene nanosheets. The three-dimensional network structure was formed, which reduced the agglomeration between graphene sheets. The hybrid of HNT and graphene sheet increased the graphene's specific surface area and constructed a three-dimensional network porous structure. Through Cyclic voltammetry (CV), Galvanostatic charge-discharge (GCD), Electrochemical impedance spectroscopy (EIS), and cycle stability tests, HGA-PANI had acceptable electrical properties, large capacitance, thin internal resistance, and amazing cyclical stability.