Development of visible-light-driven Ca2Fe1−xSmxBiO6 double perovskites for decomposition of Rhodamine 6G dye

• Sol–gel auto-combustion synthesis of novel Ca2Fe1−xSmxBiO6 double perovskites.
• Efficient photocatalysts for degradation of Rhodamine 6G dye.
• Dye removal efficiency was enhanced with increase in Sm3+ content in Ca2FeBiO6.
• Degradation rate was related to structural deformation and photoinduced processes.
• First order kinetic constant after 100 min of irradiation, k was 3.48 × 10−2 min−1.

The main objective of this work was to investigate, for the first time, the photocatalytic activity of double perovskite materials Ca2Fe1−xSmxBiO6 (x = 0, 0.2, 0.4, 0.6, 0.8, 1) in degradation of Rhodamine 6G under visible irradiation. For the synthesis was used sol–gel auto-combustion method with citric acid as combustion agent and ammonium bistmuth citrate as a source for bistmuth cation. Synthesized photocatalysts were structurally investigated by FT-IR spectroscopy to follow the M–O characteristic bands of double perovskite structure and X-ray diffraction (XRD) to confirm the pure phase of catalysts. The catalyst microstructure was characterized by SEM and BET surface areas were measured at the liquid nitrogen temperature by nitrogen adsorption. The Sm concentration optimization yielded an efficient photocatalyst. Surprisingly, the two ends of the series, i.e., Ca2FeBiO6 and Ca2SmBiO6 photocatalysts, are much more active in visible light to the degradation of pollutant Rhodamine 6G than samarium substituted Ca2FeBiO6 materials in different percentages. At an optimum composition of Sm as x = 1 in Ca2Fe1−xSmxBiO6, the photocatalyst exhibited 3.58 times the degradation yield for Rh6G dye in presence of visible light, than its intermediare counterpart.

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