Impact of Ferroelectric Polarization on Different Semiconductors for Photoelectrochemical Application

Introducing a built-in electric field into the photoelectrochemical system is considered as an effective strategy to tune interfacial energy band bending and manipulate charge transport direction. Here, we design the hybrid ferroelectric-semiconductor structure photoanodes for water oxidation, and the BaTiO3 (BTO) is used for ferroelectric while monoclinic WO3, tetragonal TiO2, and triclinic CuWO4 for the semiconductors, respectively. After the positive poling, 3 wt % BTO–WO3 and 3 wt % BTO–CuWO4 hybrid photoanodes perform a significantly enhanced photocurrent of 68.5 and 62.9% compared with the pristine semiconductors. The efficiencies of charge separation and oxidation kinetics of these hybrid photoanodes increase by 14–19% and 1.38–1.42 fold, and the electron transport time decreases by 16%. Further, Kelvin probe force microscopy measurements indicate that the surface potential of the hybrid structure is lower than unmodified samples, suggesting that the space charge region near the semiconductor surface has been changed and an outside built-in electric field is induced by the positive polarized ferroelectric. This vector of the electric field has a facilitating effect on band bending of the interface, especially on the semiconductor with the lower Fermi level, and the more upward bending can accelerate the photogenerated holes to migrate to the surface where the water oxidation take place.