The one-step synthesis of Mn3O4 nanoparticles at room temperature, without additional downstream processes, was carried out by reacting a solution of MnCl2 in water or alcohol with NaOH at different concentrations for 30 min. Spherical nanoparticles with sizes ranging from 30 to 54 nm were obtained. The characterization by XRD, Raman spectroscopy, and FTIR confirmed the spinel structure of Mn3O4. UV-VIS spectroscopy allowed to obtain the band gap, ranging from 2.37 to 2.89 eV. Photoluminescence spectroscopy gave evidence of multiple emission bands attributed mainly to structural defects. A greater influence of the type of solvent was observed than that of the NaOH concentration.
Sánchez-Monteza et al. (2026) studied this question.