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 ∼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.