Parallel Regulation of Charge Dynamics on Bipolar Ferroelectric Surfaces Breaks the Limits for Water Splitting Efficiency.

Ferroelectric materials, known for their non-inversion symmetry, show promise as photocatalysts due to their unique asymmetric charge separation, which separates hydrogen and oxygen evolution sites. However, the strong depolarized field induces a relaxed surface structure, which in turn directly leads to slow hole charge transfer dynamics, hindering their efficiency in water splitting. In this study, a fundamental breakthrough in dramatically enhancing the overall water-splitting activity is presented, through the synergistically regulating of the surface behaviors of photogenerated carriers, resulting in nearly perfect parallel dynamics and balanced amounts. By depositing atomic layers of TiO onto the surface of PbTiO, surface vacancies are effectively passivated, significantly prolonging the hole lifetime from 10 to 10 s. Spatially resolved transient photovoltage spectroscopy showed that improved hole dynamics led to a 180° phase shift between photogenerated electrons and holes, indicating nearly identical extraction dynamics. Notably, hole and electron concentrations increased to equivalent levels. This leads to a nearly 578-fold increment in the apparent quantum yield, resulting in significantly increased overall water-splitting rates, with a quantum yield of 5.78% at 365 nm. The strategy is also effective with AlO and SiO, demonstrating its versatility across varied materials, providing a valuable method for creating high-performance ferroelectric photocatalysts.