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/cm² 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/cm². 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. A novel stack-integrated photo-supercapacitor (PSC) thin-film device is composed of a dye-sensitized solar cell and a supercapacitor built on bi-polar anodic titanium oxide nanotube arrays. Improved supercapacitor performance is achieved through selective plasma-assisted hydrogenation treatment. A remarkable overall photoelectric conversion and storage efficiency up to 1.64% is achieved with a fast response and superior cycling capability.