Halloysite nanotubes induced synthesis of carbon/manganese dioxide coaxial tubular nanocomposites as electrode materials for supercapacitors

Halloysite nanotubes@carbon/manganese dioxide nanocomposites (HNTs@C/MnO2) with coaxial tubular structure were prepared by introducing manganese dioxide on the surface of carbon-coated halloysite nanotubes (HNTs@C). The HNTs@C nanocomposites were synthesized by hydrothermal carbonization of glucose on the surface of HNTs and further activated at high temperature to improve the degree of carbonization. The use of halloysite nanotubes can effectively induce the heterogeneous deposition of carbonaceous species on the surface of the halloysite nanotubes, and then uniformly generate MnO2 nanoflakes via the redox reaction between the carbon and potassium permanganate to construct the hybrid coaxial structure. The as-prepared hybrid materials were characterized by transmission electron microscope, Fourier transform infrared spectrum, X-ray diffraction, and thermogravimetric analysis. The specific capacitance of HNTs@C/MnO(2)3 nanocomposites can reach 274 F g(-1) at 1.25 mA cm(-2) in 1.0 M Na2SO4 electrolyte after correcting the weight percent of electroactive materials. Furthermore, the special coaxial tubular structure and the manganese dioxide nanoflakes facilitated the ion diffusion between the electrode/electrolyte interfaces. The results indicate that the novel coaxial tubular hybrid nanocomposites can be a promising candidate as electrode material for supercapacitors.