Enhanced photocatalytic activity of layered perovskite oxides Sr2.7-xCaxLn0.3Fe2O7-δ for MB degradation

Abstract

The photocatalytic properties of the layered perovskites belonging to n = 2 series of Ruddlesden ‒ Popper oxides Sr2.7-xCaxLn0.3Fe2O7-δ with x = 0 and 0.3, and Ln = La and Nd have been studied by monitoring the degradation of methylene blue (MB) dye under solar and UV irradiation. The Sr2.7-xCaxLn0.3Fe2O7-δ samples were synthesized by a conventional solid-state reaction and all the samples crystallized in a tetragonal space group I4/mmm. The microparticle analysis shows the grain size decreases with the decrease in lanthanide size. An increase in the absorption band in the UV–VIS–NIR range occurred with the decrease in lanthanide size. However, the Ca-substitution leads to a small decrease in the absorption band in the case of both lanthanides. The behavior of Sr2.7-xCaxLn0.3Fe2O7-δ samples for the photocatalytic decomposition of MB dye under UV and solar irradiation at room temperature were studied at various time intervals and their degradation efficiency was compared. The Nd doped samples exhibited slightly increased dye degradation under both UV and solar irradiation and is due to an increased absorbance and low band gap compared to La doped samples. Moreover, the generation of reactive oxygen species (·OHs) was confirmed by the scavenger technique. The MB degradation rate was fast under solar irradiation (180 min) compared to UV irradiation (300 min). The results presented here suggest that the Sr2.7-xCaxLn0.3Fe2O7-δ samples could be a suitable candidate for the degradation of dye contaminants in waste water under solar exposure.