3D structured Mn2O3 synthesized using tween surfactant: influence on the morphology and oxygen reduction catalytic performance

Abstract

3D structured Mn₂O₃ with flower-like (Mn₂O₃-F), globe-like (Mn₂O₃-G) or rhombohedral (Mn₂O₃-R) morphologies were successfully synthesized by solvothermal method by controlling the amounts of Tween surfactant. These Mn₂O₃ oxides enhance the catalytic activity for the oxygen reduction reaction (ORR) in direct methanol fuel cells (DMFCs) significantly, while PtRu/C works as the anode catalyst and polymer fiber membrane (PFM) functions as the electrolyte film. Mn₂O₃-G shows higher ORR catalytic activity than Mn₂O₃-F and Mn₂O₃-R. The maximum power density (P_max) of Mn₂O₃-F-, Mn₂O₃-G- and Mn₂O₃-R-based DMFCs are 11.44, 21.03 and 10.22 mW cm⁻² at room temperature, respectively. The influence of the Tween surfactant on the microstructure and ORR properties were also studied systematically. Compared with Mn₂O₃-F and Mn₂O₃-R, the Raman and XPS results indicate that Mn₂O₃-G has more oxygen vacancies, which can promote the electrical conductivity and act as an active center to absorb and store available O₂ for stable ORR properties.