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

Abstract

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.

Design Considerations for Unconventional Electrochemical Energy Storage Architectures

“…[ 700,701 ] Extra-and intra-structural device integration, as discussed above, is easier to realize yet, presents some intrinsic drawbacks. [ 694,702,703 ] The potential of constructing one of the two devices on top of the other, has been recently demonstrated by painting a LIB on top of prefabricated solar cells.…”

NiCo2S4 nanoparticles anchored on reduced graphene oxide sheets: In-situ synthesis and enhanced capacitive performance

“…Recently, great attention has been paid to the advanced energy storage systems due to the ever-increasing demands of energy sources and environmental issues [1][2][3][4][5]. Among various energy storage devices, supercapacitors are attractive because of their unique superiorities such as high power density, fast chargedischarge process, and long cycle life [6][7][8][9].…”

Theoretical analysis and characterization of the energy conversion and storage efficiency of photo-supercapacitors

“…However, the experimental determination of a PSC's discharge ECSE max requires to identify the time t Emax . The four previous studies [10,11,14,15] that report the evolution of ECSE as a function of time in their systems usually do so by repeating the charge/discharge experiments for varying times of charge. While exact, this method can be long and may induce degradations of the system due to the electrical cycling of the supercapacitor and of the prolonged light exposure of the solar cell.…”

“…A typical figure of merit of PSC is the energy conversion and storage efficiency (ECSE) over a complete charge-discharge cycle, sometimes also called "overall efficiency" [5,10] or "photoelectric conversion and storage efficiency" [8,11]. The ECSE of a PSC is measured by performing a charge-discharge experiment: during the charging phase, the solar cell is exposed to light, which charges the initially empty supercapacitor.…”

“…In order to identify this maximum, multiple charge-discharge experiments must be performed, each with a different charging time, which can be problematic if the solar cell's efficiency changes during the prolonged light exposure. While the maximum ECSE of a PSC cannot be higher than its solar cell's power conversion efficiency (PCE), the relation between the two can vary widely: in previous work [10,11,[14][15][16], the ratio ECSE/PCE can go as low as 0.12 [16] and as high as 0.81 [15].…”