Synthesis of porous manganese oxides bars via a hydrothermal-decomposition method

Porous manganese oxides with regular bar shape were synthesized by a hydrothermal-decomposition method. Uniform bar-shaped precursor was first obtained via a hydrothermal route. After annealing, porous manganese oxides with maintained macroscopic shape were synthesized. X-ray diffractometer (XRD), scanning electron microscope (SEM) and TG-DTA analysis were used to characterize the composition, structure and morphology of the samples. The porous structure was assembled by crystallites with nanosize. It was demonstrated that the annealing temperature and the heating rate play the key function in the formation of the pores. N2 physisorption results showed that the BET surface area of the manganese oxides annealed at 400 °C was 30.86 m2 g−1 and the BJH pore size distribution showed a bimodal structure with porosity on the 10 and 100 nm length scales. Macroporous Mn2O3 was synthesized at 600 °C and 800 °C. The structure of manganese tartrate was also considered to understand the possible formation mechanism of the regular shape and the porous structure.