“…There are many ways available for Mn 3 O 4 preparation, such as meteorological growth [9], radiation [10], electric arc furnace [11], co-precipitation [12], and hydrothermal/solvothermal synthesis [13]. Among them, hydrothermal/solvothermal method possesses advantages of mild reaction condition and well-controlled size, morphology and structures, which has been adopted successfully in the synthesis of various nanometer-sized oxides, metals, semiconductors and magnetic compos-ites [14,15].…”