High-performance supercapacitors based on amorphous C-modified anodic TiO₂ nanotubes

Highly ordered TiO₂ nanotube arrays were prepared by electrochemical anodization and annealed in air to transform into the anatase. Carbon modification was performed on the anatase TiO₂ nanotubes by heating in a methane flow at different temperature (300, 400, 500 and 600 °C, respectively). The C-modified TiO₂ retained their nanotubular morphology and anatase crystallinity. Furthermore, greatly improved performance as supercapacitor electrodes was enabled by the C-modification treatment. In particular, compared to the pristine TiO₂, ∼33-fold increase in specific capacitance with good cycling stability were observed on the C-modified TiO₂ nanotubes treated at 600 °C.