| 초록 |
Photoelectrochemical (PEC) cells using Cu2O, semiconductor photoabsorbers passivated by protection layers, show a trade-off between high photocurrent and durable stability because of the thickness of the energy band transport along the conduction band. Based on nanofilaments with non-volatile metal-like current flow characteristics in resistance-change memory devices, we propose a strategically advanced conducting filament transport mechanism for vigorous and robust PEC operation. The breakdown-like electrochemical forming behavior effectively occurs with a rapid increase in current at ~2 V (vs. RHE). The fundamental properties of filaments, such as diameter, density, and conductivity, were controlled by varying the artificial compliance currents. This process does not require any top electrodes that obstruct light-harvesting and the injection of photo-charges into electrolytes or individual forming process with point-by-point sweeping, and provides electrochemical forming sites with homogeneous and dense distribution. Additionally, some photocorrosive sites that induce photocurrent degradation are passivated by the preferential photoelectrodeposition of co-catalysts. From the electrochemical filament forming process and selective Pt-photoelectrodeposition on filaments, the Cu2O/AZO/TiO2 photocathodes exhibit an unprecedented photocurrent density of approximately 11.9 mA/cm2 and open-circuit potential of 0.73 V and produces vigorous hydrogen and oxygen evolutions for over 100 h, even when the TiO2 passivation film exceeds 100 nm in thickness. |
