LAUSR

Abstract Photocatalytic decomposition of methylene blue was attempted over as-prepared Mn(II)Cr(III)-layered double hydroxide (LDH) containing Mn(II) and Cr(III) in 2:1 molar ratio. The LDH was prepared by the co-precipitation method, and was found to form at pH = 10 and at 80 °C following 24 h hydrothermal treatment. The Mn 2 Cr-LDH thus obtained was structurally characterized by X-ray diffractometry, scanning electron microscopy and energy-dispersive X-ray spectroscopy. The Mn 2 Cr-LDH displayed significant photocatalytic activity in the degradation of methylene blue under illumination with UV–vis light. The photocatalytic performance of the phase-pure and uncalcined Mn 2 Cr-LDH is practically identical to that of the commercially available Degussa P25 TiO 2 , and it was found to remain unaltered over five consecutive photocatalytic runs. The presence of the LDH structure in the composite is the prerequisite of the photocatalytic activity. Applying increasing calcination temperature, the LDH structure gradually collapses, and the Mn 2 Cr-LDH transforms to photocatalytically inactive double oxide.