Piezoelectric polarization assisted WO3/CdS photoanode improved carrier separation efficiency via CdS phase regulation. (22nd October 2021)

• Record Type: Journal Article
• Authors: Zhao, Quanyou; Liu, Zhifeng; Li, Junwei; Yan, Weiguo; Ya, Jing; Wu, Xiangfeng
• Is Part Of: International journal of hydrogen energy. Volume 46:Number 73(2021)
• Page Start: 36113
• Page End: 36123
• Publication Date: 2021-10-22
• Subjects: WO3 -- CdS -- Phase transition -- Piezoelectric polarization -- Photoelectrochemical water splitting; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2021.08.123
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: 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 β-CdS to wurtzite α-CdS on piezoelectric polarization for WO3 /CdS. Benefited from the asymmetric structure of α-CdS, fluctuation swings can be seen in the LSV curves of WO3 /α-CdS due to piezoelectric polarization under ultrasound. The photocurrent density of WO3 /α-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 /α-CdS under ultrasonic conditions are contributed to carrier separation driven by enhancing internal electric field between heterojunction, the built-in electric field inside the α-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. Highlights: WO3 /α-CdS and WO3 /β-CdS were used as photoanode in PEC water splitting. CdS as the primary light absorber improves the light utilization efficiency. WO3 /α-CdS heterojunction is built to further carrier separation and transfer driven by internal electric field. Piezoelectric polarization of α-CdS provides another built-in electric field which reduces the recombination of carriers. The ballast carriers generated by piezoelectric polarization participates in the water splitting reaction.