Simultaneous Enhancement of Charge Separation and Hole Transportation in a TiO2–SrTiO3 Core–Shell Nanowire Photoelectrochemical System

Efficient charge separation and transportation are key factors that determine the photoelectrochemical (PEC) water‐splitting efficiency. Here, a simultaneous enhancement of charge separation and hole transportation on the basis of ferroelectric polarization in TiO 2 –SrTiO 3 core–shell nanowires (NWs) is reported. The SrTiO 3 shell with controllable thicknesses generates a considerable spontaneous polarization, which effectively tunes the electrical band bending of TiO 2 . Combined with its intrinsically high charge mobility, the ferroelectric SrTiO 3 thin shell significantly improves the charge‐separation efficiency (η separation ) with minimized influence on the hole‐migration property of TiO 2 photoelectrodes, leading to a drastically increased photocurrent density ( J ph ). Specifically, the 10 nm‐thick SrTiO 3 shell yields the highest J ph and η separation of 1.43 mA cm −2 and 87.7% at 1.23 V versus reversible hydrogen electrode, respectively, corresponding to 83% and 79% improvements compared with those of pristine TiO 2 NWs. The PEC performance can be further manipulated by thermal treatment, and the control of SrTiO 3 film thicknesses and electric poling directions. This work suggests a material with combined ferroelectric and semiconducting features could be a promising solution for advancing PEC systems by concurrently promoting the charge‐separation and hole‐transportation properties.