Enhanced supercapacitance in anodic TiO2 nanotube films by hydrogen plasma treatment

One-dimensional anodic titanium oxide (ATO) nanotube arrays hold great potential as electrode materials for high-performance electrochemical supercapacitors. However, their poor electronic conductivity limits their practical applications. Here, we develop a hydrogen (H2) plasma treatment method to greatly improve the electrochemical performance of ATO electrodes. Compared with pristine ATO, the nanotubes treated by H2 plasma illumination (ATO-H) present a rough and amorphous layer at the surface of the nanotubes with simultaneously incorporated Ti(3+) and -OH groups. At a current density of 0.05 mA cm(-2) in charge-discharge measurements, the specific capacitance of the ATO-H electrode has substantially increased ~7.4 times, with a value as high as 7.22 mF cm(-2). Moreover, the novel ATO-H electrode has also exhibited excellent rate capability (6.37 mF cm(-2) at a current density of 2 mA cm(-2)) and cycling performance with no degradation after 10,000 cycles.