Carbon nanotube/hematite core/shell nanowires on carbon cloth for supercapacitor anode with ultrahigh specific capacitance and superb cycling stability

Abstract

Rationally designed carbon-based conductive nanostructures are highly demanded to improve the electrochemical performance of hematite-based supercapacitors. In this research, we have successfully designed and synthesized three-layer sandwiched core–shell carbon nanotubes/Fe2O3@carbon arrays on carbon cloth substrate via commercially available magnetron sputtering and chemical vapor deposition methods. The carbon nanotube core (prepared by chemical vapor deposition) and the carbon shell (prepared by magnetron sputtering) both can improve the specific surface area and electrical conductivity of Fe2O3 (prepared by magnetron sputtering), restrain the active materials and thus enhance its electrochemical performance and long-term stability. X-ray diffraction and Raman results demonstrate the obtained hematite is α phase. Scanning electron microscopy and high-resolution transmission electron microscopy images indicate the Fe2O3 and carbon shell are conformally coated on the carbon nanotube core. Consequently, under the optimal mass of Fe2O3 and carbon shell, the carbon nanotube/Fe2O3@carbon composite electrode exhibits a high specific capacitance of 787.5Fg−1 at the scan rate of 5mVs−1 and a high stability (92% of the initial capacitance remains after 7000 cycles). The remarkable performance of these binder-free carbon cloth/carbon nanotube/Fe2O3@carbon electrodes suggest their huge potential use as negative electrode material for high performance supercapacitors.