Ultrasonically prepared photocatalyst of W/WO3 nanoplates with WS2 nanosheets as 2D material for improving photoelectrochemical water splitting

Meysam Tayebi; Zohreh Masoumi; Byeong-Kyu Lee

doi:10.1016/j.ultsonch.2020.105339

Ultrasonically prepared photocatalyst of W/WO₃ nanoplates with WS₂ nanosheets as 2D material for improving photoelectrochemical water splitting

Ultrason Sonochem. 2021 Jan:70:105339. doi: 10.1016/j.ultsonch.2020.105339. Epub 2020 Sep 6.

Authors

Meysam Tayebi¹, Zohreh Masoumi¹, Byeong-Kyu Lee²

Affiliations

¹ Department of Civil and Environment Engineering, University of Ulsan, Ulsan, South Korea.
² Department of Civil and Environment Engineering, University of Ulsan, Ulsan, South Korea. Electronic address: bklee@ulsan.ac.kr.

Abstract

A sonochemical treatment has been an emerged technique as an interesting method for fabricating different photocatalysts with unique photoelectrochemical (PEC) properties. This study investigated the PEC performance of WO₃ with WS₂ nanosheets as a 2D material before calcination (WO₃/WS₂-90) and after calcination (WO₃/WS₂-450) prepared with sonochemical treatment. The WS₂ nanosheets were prepared from a liquid exfoliation phase with few-layer nanosheets, approximately 6.5 nm in thickness. The nanosheets were confirmed by UV-Vis spectroscopy and atomic force microscopy. Further, XPS, RAMAN, and SEM-EDAX analyses indicated that, following calcination of the WO₃/WS₂ electrode, the WS₂ nanosheets initially transformed to 2D-WO₃. After depositing the WS₂ nanosheets on the WO₃, the photocurrent density increased substantially. The WO₃/WS₂-450 films after calcination showed a photocurrent density of 5.6 mA.cm^-2 at 1.23 V vs. Ag/AgCl, which was 3.1 and 7.2 times higher, respectively than those of the WO₃/WS₂-90 before calcination and pure WO₃. Mott-Schottky and electrochemical impedance spectroscopy analyses confirmed the fabrication of the WO₃/WS₂ photoanode after calcination. The deposition of WS₂ nanosheets onto pure WO₃ increased the donor concentration (24-fold), reduced the space charge layer (4.6-fold), and decreased the flat band potential (1.6-fold), which could all help improve the photoelectrochemical efficiency. Moreover, the incorporation of WO₃ with WS₂ nanosheets as a 2D material (WO₃/WS₂-450) enhanced the incident photon current efficiency (IPCE) by 55%. In addition, the applied-bias photon-to-current conversion efficiency of the WO₃/WS₂-450 films was approximately 2.26% at 0.75 V (vs. Ag/AgCl), which is 5.6 and 9 times higher, respectively than those of WO₃/WS₂-90 and pure WO₃.

Keywords: Photoelectrochemical; Ultrasonic; W/WO(3)/WS(2) electrode; WS(2) nanosheets.