FeOOH interlayer with storing holes applied to construct WO3/FeOOH/Cu2O ternary heterojunction photoanode with dual built-in electric filed for efficient PEC cell

Broader visible light response, higher carrier separation efficiency and injection efficiency are extremely important methods to enhance photoelectrochemical (PEC) performances of WO3. In this work, FeOOH with the property of storing holes is firstly applied to modify WO3/Cu2O heterojunction as an interlayer, and the WO3/FeOOH/Cu2O ternary heterojunction with excellent PEC performances is obtained. The separation efficiencies of photoinduced carrier in bulk is enhanced to 29.33% with the formation of dual built-in electric filed as well as the storage of photoinduced carriers transferred from WO3 in FeOOH, which is 3.27 folds higher than that of bare WO3. With the synergistic effect of expanded light absorption and accelerated charges transfer, the photocurrent density of 2.14 mA/cm2 at 1.23 V vs. RHE is achieved by WO3/FeOOH/Cu2O ternary heterojunction. This work can be applied for reference to improve the PEC performance of other photoelectrodes through adequate utilization of storing holes interlayer.