Effect of ferroelectric polarization field on different carrier migration in photoanode

Spontaneous polarization field in ferroelectric can improve the oxidation kinetics and photocurrent of a photoanode in photoelectrochemical water splitting. But the impact of ferroelectric polarization field on the migration of different charge carriers which have different mobility and diffusion length is still unknown. In this work, we synthesized tetragonal BaTiO3 nanoparticles by solvothermal method successfully and fabricated the hybrid photoanode composed by monoclinic WO3 and BaTiO3 for solar water oxidation. Density functional theory calculations showed that the mobility of electron was faster than that of the hole in WO3, and had a longer diffusion length. We demonstrated that the polarization field of ferroelectric had a greatly impact upon holes migration compared with electrons, thus the thin hybrid photoanode after poling by bias presented a significant improvement of photocurrent (210.5%) under the back-side illumination, and a remarkable augment of charge separation efficiency (94%) and oxidation kinetics (69%) at 1.23 V. Our work provided a deeper understanding of how ferroelectric polarization field affected the photoelectrochemical water oxidation and a general pathway towards enhancing minority carrier collection in photoanode.