Ag-doped BiVO4/BiFeO3 photoanode for highly efficient and stable photocatalytic and photoelectrochemical water splitting

Tayyebeh Soltani; Byeong-Kyu Lee

doi:10.1016/j.scitotenv.2020.138640

Ag-doped BiVO₄/BiFeO₃ photoanode for highly efficient and stable photocatalytic and photoelectrochemical water splitting

Sci Total Environ. 2020 Sep 20:736:138640. doi: 10.1016/j.scitotenv.2020.138640. Epub 2020 Apr 19.

Authors

Tayyebeh Soltani¹, Byeong-Kyu Lee²

Affiliations

¹ Department of Civil and Environmental Engineering, University of Ulsan, Nam-gu, Daehak-ro 93, Ulsan 44610, Republic of Korea; Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501, Japan.
² Department of Civil and Environmental Engineering, University of Ulsan, Nam-gu, Daehak-ro 93, Ulsan 44610, Republic of Korea. Electronic address: bklee@ulsan.ac.kr.

PMID: 32487354
DOI: 10.1016/j.scitotenv.2020.138640

Abstract

In a conventional photoelectrochemical (PEC) water splitting system using BiVO₄ (BVO), most of the charge carriers have very sluggish photocatalysis reaction kinetics because they are easily recombined from the defects developed from the bulk or the surface of the photoanodes before reaching the fluorine-doped tin dioxide (FTO). Herein, we present a facile design and fabrication technique for a Ag-BVO/BiFeO₃ (BFO) heterostructure photoanode by Ag doping and surface passivation with BFO on the as-preparedBVO photoanode. Its photocatalytic properties for PEC water splitting and tetracycline (TC) degradation are compared to those of BVO/BFO, BVO, and Ag-BVO photocatalyst nanoparticle (NP) films. The effect of Ag-doping/BFO surface passivation on the morphological, structural, and optical properties and surface electronic structure of the as-obtainedBVO electrodes was investigated. The photocatalytic degradation of TC in aqueous solution by Ag-BVO/BFO was greatly increased (>1.5-fold) compared to that of BVO. The TC was completely photodegraded in 50 min of visible-light irradiation. The as-preparedAg-BVO/BFO heterojunction photoanode not only exhibited 4-fold higher PEC performance (0.72 mA cm^-2 vs. RHE) and stability than those of the pure BVO components, but also the onset potential in the Ag-BVO/BFO photoanode was cathodically shifted by 600 mV compared to that of the bare BVO. The Ag-BVO/BFO photoelectrode with the highest donor density and the lowest charge transfer resistance exhibited a 4.46-fold higher carrier density than that of the pure BVO photoelectrode. More specifically, the Mott-Schottky (MS) and electrochemical impedance spectroscopy (EIS) results demonstrated that the Ag-doping not only effectively increased the carrier charge density of BVO, thus increasing the consumption rate of charge carriers, but also increased the charge transfer and transport efficiencies of the BVO photoanodes.

Keywords: Ag-BVO/BFO nanocomposite; Charge carrier; Green and sustainable energy; PEC water splitting; Photocurrent.