Highly dispersed SmMn2O5 nanorods for electrochemical water oxidation reaction kinetics

Abstract

Highly dispersed SmMn2O5 nanorods were successfully grown by using facile solvothermal route with optimized 15 M NaOH concentration. Orthorhombic single-phase SmMn2O5 was confirmed by (211) crystal plane from x-ray diffraction study. Formation of uniform nanorods was confirmed by field-emission scanning electron micrograph images. Phonon vibrations and Mn-O vibration modes were observed around 600 cm−1 in Raman and Fourier transform infrared spectra. Presence of oxygen vacancies in highly dispersed SmMn2O5 nanorods was confirmed by photoluminescence spectra by the observed emission peaks around 493 and 520 nm. Magnetic transformation from dia- to paramagnetic behavior was revealed for SmMn2O5 nanorods with respect to the increasing concentration of NaOH precipitating agent used in the material synthesis. Electrochemical water oxidation kinetics of optimized highly dispersed SmMn2O5 nanorods were investigated by a cyclic voltammogram and the specific capacitance value was calculated as 352 F g−1 at 10 mV s−1 scan rate. Oxygen evolution reaction (OER) of highly dispersed SmMn2O5 nanorods was calculated by a liner sweep voltammogram and found to be 178 mA g−1 with a lower internal resistance of 1.5 Ω. The long-term stability of the optimized SmMn2O5 electrode was achieved with 71% retention after 16 h of OER activity.