Tailored synthesis of well-faceted single crystals of Fe3O4 and their application in p-nitrophenol reduction

Abstract

Well-defined Fe₃O₄ nanocrystals (NCs), which exhibit excellent catalytic properties, have been synthesized in high yield via a facile hydrothermal method. Both the type of hydramine and concentration of NaOH play important roles in the formation of the Fe₃O₄ NCs with various morphologies. Detailed investigations indicated that the cubic and polyhedral Fe₃O₄ NCs can be prepared by adjusting the concentration of the triethanolamine (TEOA) in solution. The addition of increasing amounts of NaOH was found to facilitate the morphology transition from Fe₃O₄ cube shape to octahedron shape. The catalytic performances of these prepared samples have been investigated by reducing p-nitrophenol into p-aminophenol by an excess of N₂H₄ without the assistance of noble metals. The kinetics of the reduction reaction at different temperatures was also investigated to determine the activation parameters. Importantly, the obtained (100) faceted Fe₃O₄ nanocubes exhibits significantly higher catalytic activities than (111) faceted Fe₃O₄ octahedrons and bulk Fe₃O₄ nanoparticles, and these catalysts are stable and can be easily recycled.