Soft synthesis and analysis of structural parameters upon photoactivity of visible-active BiVO4-based ternary heterojunctions

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Abstract

Cu2O/Pt–BiVO4 and Cu2O/Au–BiVO4 photocatalysts are synthesized using a mild reducing agent (ascorbic acid) by an in-situ chemical reduction method at 25 °C. Pt and Au nanoparticles with an approximate size from 15 to 25 nm were incorporated onto BiVO4 powders. Crystalline phases are refined with the Rietveld method to evidence whether structural parameters contribute to enhance the photoactivity of the composites. The influences of structural defects and deposited metal are investigated to establish a relationship with their photoactivities. The as-synthesized BiVO4-based ternary photocatalysts displayed a strong optical absorption from UV to visible light shorter than 514 nm, with a blue-shift compared to that of pure BiVO4, resulting from the addition of the Au and Pt nanoparticles. The photocatalytic activities of the as-synthesized materials are evaluated under visible-light irradiation using the mineralization of 4-chlorophenol (4-CP) and dicloxacillin (DCX). The mineralization percentages achieved with Cu2O/Pt-BVO4 and Cu2O/Au–BiVO4 after 240 min of irradiation were 85% for 4-CP and 33% for DCX. It is assumed that those levels of TOC removal are due to the lowest content of oxygen vacancies in the photocatalysts, decreasing hole trapping, and subsequently hindering their recombination with the photoexcited electrons. Under this premise, structural defects (i.e. oxygen deficiency) present a more important effect on the photoactivity of the BiVO4-based materials than crystallite size, or other structural parameters. Moreover, the activity can also be ascribed to the Z-scheme Cu2O/BiVO4 heterojunction enhancing redox potentials of charge carriers, the incorporation of Pt and Au nanoparticles, enhancing charge separation either by trapping photo-generated electrons, generating the electron sink effect.
Original languageEnglish
Article number108306
Number of pages9
JournalMaterials Science in Semiconductor Processing
Volume176
Issue number15
DOIs
Publication statusPublished - 15 Jun 2024

Keywords

  • Cu O/BiVO heterostructure
  • Oxygen vacancy
  • Photocatalysis
  • Recalcitrant pollutants
  • Visible-light

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