Piezoelectric polarization-induced internal electric field manipulation of the photoelectrochemical performance in Nd, Co codoped BiFeO3

Abstract

Developing piezo-phototronic photocatalysts to substitute conventional photocatalysts may be an extremely challenging strategy for the effective photoeletrochemical (PEC) splitting of water. The coupling of piezoelectric polarization and semiconductor characteristics provides a feasible means to control charge transfer, recombination, or separation through the application of external strain. Herein, we used piezoelectric polarization as a built-in electric field to promote the separation of BiFeO₃ photocarriers. Furthermore, we fabricated a Nd, Co co-doped BiFeO₃ photoelectrode to reduce the band gap and enhance the absorption of solar light. In this study, the as-fabricated Bi_0.8Nd_0.2Fe_0.9Co_0.1O₃ displayed an excellent photocurrent density of 2.48 mA cm⁻² at 1.23 V vs. RHE, which was 4.42 times that of BiFeO₃. After the Bi_0.8Nd_0.2Fe_0.9Co_0.1O₃ was excited by the piezoelectric effect, its photocurrent density was 3.66 mA cm⁻² at 1.23 V vs. RHE, which was 1.48 times that before the ultrasound treatment. The modification of Bi_0.8Nd_0.2Fe_0.9Co_0.1O₃ improved the charge separation and transfer efficiency and achieved a better visible response and piezoelectric polarization, providing another way for water splitting. Hence, the mechanism solved the above key challenges and provides a promising strategy for solar-driven photoelectrochemical water splitting.