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.