Piezoelectric polarization assisted WO3/CdS photoanode improved carrier separation efficiency via CdS phase regulation

The key factor for efficient photoelectrochemical (PEC) water splitting is to design a semiconductor as photoanode with high carrier separation. Piezoelectric polarization is a considerable method to improve the carriers separation efficiency via providing a powerful built-in electric field. Herein, we synthesized WO3/CdS type II heterojunction and firstly explored the influence of CdS phase transition from sphalerite beta-CdS to wurtzite alpha-CdS on piezoelectric polarization for WO3/CdS. Benefited from the asymmetric structure of alpha-CdS, fluctuation swings can be seen in the LSV curves of WO3/alpha-CdS due to piezoelectric polarization under ultrasound. The photocurrent density of WO3/alpha-CdS are enhanced with the increase of ultrasound frequency and the maximum of 2.13 mA/cm(2) at 1.23 V vs. RHE, which is 1.61 times before ultrasound. The outstanding PEC performances of WO3/alpha-CdS under ultrasonic conditions are contributed to carrier separation driven by enhancing internal electric field between heterojunction, the built-in electric field inside the alpha-CdS and ballast carriers participating in water splitting reaction. This work provides a promising strategy for improving carrier separation efficiency in photoelectrodes via piezoelectric polarization. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

The study focused on synthesizing WO3/CdS II heterojunction and investigating the influence of CdS phase transition on piezoelectric polarization. Enhanced photocurrent density of WO3/alpha-CdS was observed under ultrasound due to piezoelectric polarization, indicating a promising strategy to improve carrier separation efficiency in photoelectrodes.