Microscopic Insight into the Polarization-Dependent\nOxygen Evolution Reaction on the Surface of Intrinsic Ferroelectric\nSemiconductor β‑CuGaO<sub>2</sub>

Ferroelectric\nsemiconductors hold great promise in the field of\nphotocatalysis due to their spontaneous polarization that can suppress\nthe recombination of photogenerated charges, but the mechanism of\nthe effect of ferroelectric polarization and the intensity of polarization\non surface catalytic reactions have never been approached. Here, we\nhave comparatively investigated the oxygen evolution reaction (OER)\ncatalytic process on surfaces in polarized and unpolarized orientations\nof the intrinsic ferroelectric semiconductor β-CuGaO<sub>2</sub> by first-principles calculations. Furthermore, semiquantitative\neffects of different polarization intensities on the OER on the surfaces\nare subsequently carried out. First, it is confirmed that the [011]-polarized\nsurface with fully exposed Cu–O atoms is the easiest surface\nto form and the most attractive for water molecules, exhibiting the\nlowest OER free energy barrier of 1.71 eV. Second, the calculated\nresults indicate that [011] surfaces with higher polarization intensity\nare capable of enhancing the photogenerated hole potential (<i>U</i>) due to the accumulation of microscopic polarization in\nthe polar unit of the bulk phase within the [011] slab. The intrinsic\nmechanism behind the enhancement of the OER by ferroelectric polarization\nis attributed to the modulation effect of polarization intensity on\nthe 3d orbit of Cu<sup>+</sup>. This work elucidates the effects of\nferroelectric polarization orientations as well as polarization intensity\nfor the water OER, and provides theoretical guidance for the intrinsic\nferroelectric polarization to promote surface OER.