In-Plane Ferroelectric p/n Superstructure Photoelectrode for Bias-Free Solar-Fuel Conversion.

Zhao, Jia; Wang, Aiji; Liu, Huiya; Qi, Xugang; Hao, Rui; Shao, Jialin; Luo, Lili; Tao, Kun et al. · Nano Lett · 2025

basic_science · Level V

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Abstract

Multijunction photoelectrodes, which generate active photocarriers with sufficient energy to drive unassisted solar-fuel conversion, represent a promising avenue for sustainable energy applications. However, achieving controllable p/n-type doping and high-quality growth remains a challenge for most emerging metal oxide semiconductors. In this study, we demonstrate the creation of in-plane ferroelectric p/n homojunction superstructures in BiFeO<sub>3</sub> (BFO) films, enabling bias-free photoelectrochemical (PEC) reactions. By leveraging in situ oxygen vacancy (V<sub>O</sub>) engineering, we enabled reversible switching between p- and n-type conductivity in BFO, thereby constructing p/n superstructures with densely packed depletion regions. Consequently, the superstructure achieves a dramatic improvement in carrier collection efficiency, as evidenced by an increased H<sub>2</sub>O<sub>2</sub> production (8.6 times higher than that of p-BFO and 16.7 times higher than that of n-BFO). Furthermore, selective catalyst deposition on the p- and n-regions facilitates bias-free water splitting. The approach is readily adaptable to other ferroelectric materials, where V<sub>O</sub>-mediated conductivity modulation is feasible.