Modification of Ag₈SnS₆ Photoanodes with Incorporation of Zn Ions for Photo-Driven Hydrogen Production

• Main Authors: Lin-Ya Yeh, Kong-Wei Cheng
• Format: Article
• Language: English
• Published: MDPI AG 2021-03-01
• Series: Catalysts
• Subjects: hydrogen production; metal sulfide; photoelectrochemical performance; hall measurement; optical properties
• Online Access: https://www.mdpi.com/2073-4344/11/3/363

In this study, Zn ions were incorporated into Ag₈SnS₆ thin films on glass and indium–tin–oxide-coated glass substrates using chemical bath deposition. Detailed procedures for the growth of Ag–Zn–Sn–S semiconductor films and their optical, physical and photoelectrochemical performances were investigated. X-ray diffraction patterns of samples revealed that kesterite Ag₂ZnSnS₄ phase with a certain amount of Ag₈SnS₆ phase can be obtained using ethylenediaminetetraacetic acid disodium salt and trisodium citrate as the chelating agent couples. Images of field-emission scanning electron microscope showed that plate-like microstructures with some spherical aggregates were observed for the sample at low Zn content. It changed to irregular spherical grains with the [Zn]/[Sn] ratios being higher than 0.95 in samples. The energy band gaps of the samples were in the range of 1.57–2.61 eV, depending on the [Zn]/[Sn] molar ratio in sample. From the Hall measurements, the carrier concentrations and mobilities of samples were in the ranges of 6.57 × 10¹²–1.76×10¹⁴cm⁻³ and 7.14–39.22 cm²/V·s, respectively. All samples were n-type semiconductors. The maximum photoelectrochemical performance of sample was 1.38 mA/cm² in aqueous 0.25 M K₂SO₃ and 0.35 M Na₂S solutions.