Rare earth metal (Sm)-doped NiMnO₃ nanostructures for highly competent alkaline oxygen evolution reaction

Abstract

In the present work, samarium-doped nickel manganese oxide was produced by employing a straightforward co-precipitation method. A peak with a 2<i>θ</i> of 36° corresponded to the (110) plane confirming the formation of the rhombohedral crystal structure of NiMnO₃. The existence of Mn-O and Ni-O stretching vibration modes was confirmed by Raman spectroscopy. FTIR spectra confirmed the existence of the metal-oxygen bond of NiMnO₃. The synthesized ternary Ni-based material was found to be spherical nanoparticles with an average diameter of 0.81 μm. The electrochemical oxygen evolution reaction (OER) performance was explored on 0.02 M samarium (Sm)-doped NiMnO₃ demonstrating outstanding OER action with low 321 mV, a low Tafel slope value (109 mV dec^-1), and low charge-transfer resistance (0.19 Ω). Moreover, the BET results suggest that the 0.02 M Sm-doped NiMnO₃ exhibited elevated surface area (78.78 m² g^-1) with a mesoporous character. Therefore, NiMnO₃ doped with high concentrations of a rare earth metal, Sm, is proposed as a suitable material for next-generation water splitting applications.