| 초록 |
The design to control grain boundaries (GBs) causing recombination losses as planar defects in the absorbing layers is an essential strategy for the development of highly efficient photoelectrochemical (PEC) reaction systems. We propose a method to design a progressive bundle-type columnar structure as an alternative to single crystals with the least defects, where the GBs are parallel to the charge transport movement and the electric field direction. An instant strike bias (0.01 s and −1 V vs Ag/AgCl) in the same electrolytes induces the formation of island-shaped metallic Cu nanoparticles in the initial stage. These act as seed crystals for controlling Cu2O growth evolution, resulting in dramatically high-density Cu2O nuclei. This is followed by the deposition of bundle-type columnar Cu2O with longitudinal GBs, contrary to the typical randomly crystallized Cu2O. Metallic Cu seeds with a stronger electric field than that of the exposed indium tin oxide (ITO) region provide selective crystallization sites for Cu2O growth along the ⟨111⟩ ionic bonding. Despite the instant strike interval, the p-type Cu2O photoelectrodes retained an outstanding photocurrent density of 5.2 mA cm–2 at 0 VRHE and an onset potential of 0.7 VRHE because of the highly improved charge transport and transfer efficiencies inside Cu2O induced by effectively suppressing charge scattering in the GBs. The impedance measurements depict the overall decrease in the total resistance, charge-transfer resistance, and the photoabsorber/electrode interface resistance of the PEC systems with the introduction of the instant strike process |
