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Simultaneous Enhancement of Charge Separation and Hole Transportation in a TiO 2 –SrTiO 3 Core–Shell Nanowire Photoelectrochemical System

2017; Volume: 29; Issue: 28 Linguagem: Inglês

10.1002/adma.201701432

1521-4095

Fei Wu, Yanhao Yu, Huang Yang, Lazarus German, Zhenquan Li, Jianguo Chen, Weiguang Yang, Lu Huang, Weimin Shi, Linjun Wang, Xudong Wang,

Multiferroics and related materials

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.