Abstract
Porous manganese carbonate was obtained via solvothermal synthesis using ethanol and urea. The manganese carbonate was subsequently used as a precursor to synthesise mesoporous manganese oxides via thermal treatments at three various temperatures. X-ray diffraction and Extended X-ray Absorption Fine Structure (EXAFS) results shows that γ-MnO2 is synthesised at 380 and 450 °C while Mn2O3 is produced at the annealing temperature of 575 °C. X-ray absorption spectra show that γ-MnO2 converts completely to Mn2O3 after annealing over the 450–575 °C range. The oxides obtained at 380 °C and 450 °C possess extremely high specific surface area, which is of interest for catalytic applications. The oxides were investigated as electrocatalysts for the oxygen evolution reaction; the oxide prepared at the lowest annealing temperature was found to be the optimum catalyst with an overpotential of 427 ± 10 mV at a current density of 10 mA cm−2, normalised by the geometric area. The improved catalytic activity was related to the presence of defect-rich and highly porous manganese dioxide at the lowest annealing temperature.
Original language | English |
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Pages (from-to) | 780-788 |
Number of pages | 9 |
Journal | Sustainable Energy & Fuels |
Issue number | 4 |
Early online date | 12 Apr 2017 |
DOIs | |
Publication status | Published - 2017 |