Removal of rhodamine 6G dye contaminant by visible light driven immobilized Ca1-xLnxMnO3 (Ln = Sm, Ho; 0.1 ≤ x ≤ 0.4) photocatalysts

B. Barrocas, Susana Sério, A. Rovisco, Y. Nunes, M. E. Melo Jorge

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Abstract

Visible-light-driven Ca1-xLnxMnO3 (Ln = Sm, Ho; 0.1 ≤ x ≤ 0.4) films were grown by RF-magnetron sputtering onto fused silica substrates. The effects of Ca2+ substitution for Ho3+ or Sm3+ in Ca1-xLnxMnO3 on the structural, morphological and photocatalytic properties for rhodamine 6G dye degradation under visible light irradiation were investigated. XRD showed a pure typical perovskite phase for all the prepared films, except for Ca0.9Ho0.1MnO3 and a decrease of the crystallite size with the increase of the amount of ion substituted. SEM and AFM revealed that the films surface is dense, with low roughness. UV-vis spectroscopy indicated for the two series band gaps in the range of 1.6-2.8 eV, being lower for the films containing holmium. The results showed that some Ca1-xHoxMnO3 and Ca1-xSmxMnO3 films present higher photocatalytic activity for Rh6G degradation in comparison with TiO2 films and for the same x value the Ho-films exhibited higher photocatalytic activity. For both films series the maximal degradation rate was obtained for x = 0.2; above this content the degradation percentage exhibits a decreasing trend with the increase of Ho or Sm substitution, except for x = 0.4 in the case of Ho system, which is observed again an increase in the degradation rate. The Rh6G photocatalytic degradation followed a pseudo first-order reaction kinetics. XRD and SEM of the used photocatalysts evidenced high photochemical stability.
Original languageEnglish
Pages (from-to)798-806
Number of pages9
JournalApplied Surface Science
Volume360
DOIs
Publication statusPublished - 1 Jan 2016

Keywords

  • Mixed valence manganites films
  • RF-magnetron sputtering
  • Rhodamine 6G
  • Photocatalytic activities
  • Visible light irradiation
  • METAL-INSULATOR-TRANSITION
  • SEMICONDUCTOR PHOTOCATALYSIS
  • ENVIRONMENTAL APPLICATIONS
  • PEROVSKITE OXIDES
  • SURFACE SCIENCE
  • ALKALINE MEDIA
  • FILMS
  • PERFORMANCE
  • ELECTRODES
  • NANOPARTICLES

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