Integrated Photo-supercapacitor Based on Bi-polar TiO2 Nanotube Arrays with Selective One-Side Plasma-Assisted Hydrogenation

One-dimensional anodic titanium oxide (ATO) nanotube arrays hold great potential as electrode materials for both dye-sensitized solar cells (DSSCs) and electrochemical supercapacitors (SCs). In this work, a novel stack-integrated photo-supercapacitor (PSC) thin-film device is presented, composed of a DSSC and a SC built on bi-polar ATO nanotube arrays, where an improved SC performance is achieved through selective plasma-assisted hydrogenation treatment. At a high current density of 1 mA/cm(2) in charge/discharge measurements, the areal capacitance of selective hydrogenated ATO two-electrode sub-device is substantially increased approximate to 5.1 times, with the value as high as 1.100 mF/cm(2). The optimized PSC exhibits a remarkable overall photoelectric conversion and storage efficiency up to 1.64%, with fast response and superior cycling capability for more than 100 photocharge/galvanostatic discharge cycles without any decay. To meet applicable demands with a larger output voltage, a tandem PSC system is constructed, serving as the self-driven power source for an LED.