Impact of the annealing temperature on perovskite strontium doped neodymium manganites nanocomposites and their photocatalytic performances

Abstract

Abstract In the present work, Nd 0.6 Sr 0.4 MnO 3 nanocomposite perovskite has been synthesized using sol-gel method in the presence of polyethylene glycol and citric acid. As-synthesized Nd 0.6 Sr 0.4 MnO 3 perovskite was annealed at different temperatures (500–1150 °C). The obtained perovskite Nd 0.6 Sr 0.4 MnO 3 nanocomposites exhibit wide optical absorption in the UV–visible range with low bandgap values ∼ 2–2.98 eV relied on annealing temperatures. The crystalline size of the annealed sample at 500 °C was 55 nm increased with boosting temperature to 168 nm at 1150 °C. The newly prepared perovskite has been assessed by MB photodegradation under visible light. Our findings reveal that, Nd 0.6 Sr 0.4 MnO 3 perovskite with 26.18% orthorhombic and 73.82% monoclinic phases annealed at 500 °C is a superior photocatalyst than that of Nd 0.6 Sr 0.4 MnO 3 perovskite containing 82.22% cubic and 17.78% orthorhombic phases annealed at 1150 °C. 100% of MB could be photodegraded by the Nd 0.6 Sr 0.4 MnO 3 perovskite annealed at 500 °C. However, with the increase annealing temperature to 1150 °C, the photocatalytic efficiency was reduced to 60%. The overall photodegradation rate of Nd 0.6 Sr 0.4 MnO 3 perovskite annealed at 500 °C is significantly 3-times higher than that of Nd 0.6 Sr 0.4 MnO 3 perovskite annealed at 1150 °C. The superiority of the perovskite Nd 0.6 Sr 0.4 MnO 3 annealed at 500 °C is attributed to the double phases formed (monoclinic/orthorhombic) framework, high crystallinity, and the high distortion of the Mn-O polyhedron. It is believed that the high visible-light absorption, lattice distortion and narrow band gap are considered to be the key factors for the high photocatalytic activity of the obtained Nd 0.6 Sr 0.4 MnO 3 perovskite annealed at 500 °C.