LaCO3OH Nanoprisms and Their Luminescence and NO Reduction Properties

Abstract

In this work, single-crystalline large-scale LaCO3OH nanoprism morphologies were synthesized by controlling La and Ca molar ratio and the hydrothermal reaction conditions. The nanoprism morphologies of LaCO3OH were unique in nature with a sharp corner and smooth surfaces. The hydrothermal reaction was carried out in the absence of organic additives or templates and (NH4)2CO3 was used as a precipitation agent. The molar ratio of La:Ca was varied over the following values (the sample shorthand is given in parentheses): 75:25 mol% (LC-1), 50:50 mol% (LC-2), and 25:75 mol% (LC-3). Phase-pure LaCO3OH nanoprisms formed at a La:Ca molar ratio of 75:25 mol% without any assistance of catalysts or template. The photoluminescence (PL) properties of the as-synthesized powders showed one broad emission band centered at 394 nm after excitation of the pure LC-3 LaCO3OH nanoprisms at λ = 280 nm. The PL intensities were decreased in the order of LC-1 < LC-2< LC-3. The LC-1 and LC-2 samples had almost the same PL intensities probably due to their unique and smooth particle morphology. The calcination result of three samples treated for two hours at 800 °C, shows a reduction in NO activities over highly distributed CaO comprising La2O3. Further, under the presence of H2O and O2 vapor, CaO comprising La2O3 catalysts shows higher stability for the reduction of NO with CH4.