Template-Less and Surfactant-Less Synthesis of CeO 2 Nanostructures for Catalytic Application in Ipso -hydroxylation of Aryl Boronic Acids and the aza-Michael Reaction.

Due to its excellent physicochemical properties, CeO has found great importance as an electrochemical and in electronics, photocatalysis, sensing, and heterogeneous catalysis. Herein, we report the surfactant-less and template-less synthesis of CeO nanostructures by the hydrothermal method. The synthesized CeO nanostructures have been characterized in detail by electron microscopy, spectroscopy, diffractometry, and other analytical methods. The XRD studies revealed the formation of pure crystalline CeO possessing a cubic fluorite structure with an average crystallite size of 15.6 to 16.4 nm. Electron microscopy studies reveal the formation of cube-shaped CeO nanostructures with sizes below 25 nm. The cube-shaped CeO nanostructures exhibited a higher BET surface area compared to their bulk counterparts. The XPS analysis has confirmed the existence of Ce in the mixed oxidation states of +3 and +4, while O is present as O in the sample. The as-synthesized CeO nanostructures exhibit excellent catalytic activity in both the -hydroxylation of aryl boronic acids and the aza-Michael reaction. The analysis of the used catalyst has confirmed its stability under the reported reaction conditions. The catalysts retain their catalytic activity up to the fifth run in both types of reactions, which is economically beneficial for industrial application.