Reducing the vacancies associated with ferroelectric polarization to promote photocatalytic overall water splitting

Ferroelectric materials hold great promise in photocatalytic water splitting because their built-in electric field induced by the depolarization field can fulfill the separation of photogenerated carriers. However, a number of intrinsic charged vacancy defects are simultaneously generated to screen the depolarized field for stabilizing the crystal structure, always resulting in severe recombination of photogenerated carriers and thus poor overall water splitting activity. Herein, we proposed a strategy to promote the separation and transport of photogenerated carriers of ferroelectric photocatalysts by adjusting the ferroelectric polarization and altering the coordination environment of elements to reduce the defect concentration. Specifically, we prepared a series of Ta-doped PbTiO₃ with low Pb (V_Pb) and O (V_O) vacancy concentrations by reducing the polarization intensity and strengthening the Pb–O interaction. The Ta-doped PbTiO₃ shows efficient charge separation and greatly enhanced photocatalytic overall water splitting activity with the assistance of cocatalyst. This work highlights the importance of regulating ferroelectric polarization and vacancy defect concentration by the doping strategy in charge separation for photocatalytic water splitting.