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

Abstract

Broader visible light response, higher carrier separation efficiency and injection efficiency are extremely important methods to enhance photoelectrochemical (PEC) performances of WO 3 . In this work, FeOOH with the property of storing holes is firstly applied to modify WO 3 /Cu 2 O heterojunction as an interlayer, and the WO 3 /FeOOH/Cu 2 O 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 WO 3 in FeOOH, which is 3.27 folds higher than that of bare WO 3 . With the synergistic effect of expanded light absorption and accelerated charges transfer, the photocurrent density of 2.14 mA/cm 2 at 1.23 V vs. RHE is achieved by WO 3 /FeOOH/Cu 2 O ternary heterojunction. This work can be applied for reference to improve the PEC performance of other photoelectrodes through adequate utilization of storing holes interlayer. • WO 3 /FeOOH/Cu 2 O ternary heterojunction is prepared with FeOOH as interlayer for PEC water splitting. • Photocurrent density of WO 3 /FeOOH/Cu 2 O is 2.14 mA/cm 2 , which is 10.19 folds higher than that of WO 3 . • Cu 2 O particles outer layer as the primary light absorber improves the light utilization efficiency. • Ternary heterojunction with formation of dual built-in electric filed facilitates charge separation and transfer. • The effect of extracting and storing holes for FeOOH further enhance carrier separation of the heterojunction.