Three-Dimensional Hybrid Nanostructures of Fe₃O₄ Nanoparticles/Vertically-Aligned Carbon Nanotubes for High-Performance Supercapacitors

Abstract

A three-dimensional (3D) hybrid nanostructure of Fe3O4 nanoparticles uniformly anchored on vertically-aligned carbon nanotubes (VACNTs) was fabricated by a facile two-step method. Assisted by supercritical carbon dioxide (SCCO2), the Fe precursor was firstly absorbed on CNT surface and then transformed into Fe3O4 nanoparticles by vacuum thermal annealing. Owing to the synergetic effects of well-distributed Fe3O4 nanoparticles (~7 nm) and highly conductive VACNTs, the hybrid electrode exhibits a high specific capacitance of 364.2 F g−1 at 0.5 A g−1 within the potential range from −0.9 to +0.1 V in Na2SO3 electrolyte and an excellent cycling stability of 84.8% capacitance retention after 2000 cycles at a current density of 4 A/g. This 3D hybrid architecture consisting of aligned CNTs and pseudocapacitive metal oxide may be a promising electrode for high-performance supercapacitors.

Keywords

• SCCO₂
• Fe₃O₄/VACNTs
• hybrid electrode
• supercapacitor