Microstructure evolution and advanced performance of Mn3O4 nanomorphologies

Abstract

Mn₃O₄ morphologies with tetragonal single-crystal nanostructures including nanoparticles, nanorods and nanofractals were successfully prepared by a widely applicable chemical reaction route. The morphologies were synthesized using the reactants MnCl₂·4H₂O, H₂O₂, and NaOH in a suitable surfactant and alkaline solution. The dripping speed of the NaOH solution plays an important role in the microstructure evolution of Mn₃O₄ morphologies. The difference in the dripping speed of NaOH solutions leads to different Mn₃O₄ nanomorphologies, which are called nanoparticles, nanorods and nanofractals. The average grain size of the Mn₃O₄ nanoparticles ranged from a few to several tens of nanometers. The Mn₃O₄ nanorods were smooth, straight, and the geometrical shape was structurally perfect. Their lengths ranged from several hundred nanometers to a few micrometers, and their diameters ranged from 10 nm to 30 nm. The fractal branches of the Mn₃O₄ nanofractals were a few micrometers in length and several hundred nanometers in width. The catalytic properties of these Mn₃O₄ nanomorphologies for the degradation of phenol were evaluated in detail. The results indicated that the Mn₃O₄ nanofractals possess remarkable catalytic activity for the degradation of phenol in water treatment.