| 초록 |
Tungsten trioxide (WO3) has attracted much attention since it has long hole diffusion length and great photo-stability. However, WO3 suffers from high bandgap and poor surface kinetics. One strategy to overcome these limitations is to form a heterojunction with another metal oxide, which can broaden absorption range of light and manipulate the charge kinetics. In this study, we overlaid homogeneous WO3 overlayer on vertically aligned WO3 nanowires (NWs) via flame vapor deposition (FVD) process, which eventually resulted a strained overlayer. Moreover, hematite (α-Fe2O3) was grown on both sample by hydrothermal method. As a result, the morphology of hematite grown on WO3 NWs varies depending on the presence of the strained overlayer. Moreover, the introduce of overlayer resulted an enhancement in charge transport efficiency and a significant increase of photocurrent density at 1.23 V vs. reversible hydrogen electrode. Density functional theory calculation confirmed that the band shape at the near band edge was changed by strain, and thus the effective mass was reduced, resulting improved conductivity comparing to bare WO3 NWs. |
