Mn-Doped Double Perovskite/Carbon Aerogel Catalysts: Unlocking Surface Chemistry and Crystallographic Synergy for Superior Oxygen Reduction Reaction Publisher



D Sanaei DARYOUSH ; Mr Massoudinejad Mohamadreza REZA ; Mr Alipour Mohammad REZA ; H Sharifan HAMIDREZA ; G Barzegar GELAVIZH ; R Jokar ROSA ; Y Amini YAZDAN ; Nk Allam Nageh K
Source: Results in Engineering Published:2025

Abstract

Rational design and optimization of structural and electronic properties in composite materials are effective strategies to enhance the electrocatalytic oxygen reduction reaction (ORR) activity of transition metal-based perovskites. While perovskites exhibit high activity and stability, making them promising electrocatalysts for ORR, integrating an amorphous-crystalline structure presents several advantages over purely crystalline counterparts, including simplified synthesis and deeper insights into catalytic mechanisms. However, achieving this structural synergy remains a significant challenge. In this study, a double perovskite backbone, (SrCo0.5Fe0.5O₃) coated with MnOx and combined with carbon aerogel (Cg), is synthesized to create an amorphous-crystalline Mn-doped double perovskite/Cg composite. This hybrid structure demonstrates remarkable electrocatalytic activity for ORR, achieving a superior half-wave potential of 0.89 V and an onset potential of 0.97 V, outperforming the purely crystalline double perovskite/Cg counterpart. The enhanced activity is attributed to Mn doping, which regulates the Lewis acid-base properties on the surface and modifies the adsorption chemistry of reactive species. Moreover, the incorporation of Mn induces oxygen vacancies (Ov), reducing the work function of the double perovskite oxides and elevating the LUMO energy levels. The oxygen atoms bound to Mn, Fe, or Co act as stronger bases, thereby increasing the binding energy of O₂ molecules (a Lewis acid) to the Mn-doped surface. Density functional theory (DFT) calculations reveal that Mn doping facilitates the formation of Lewis acid-base pairs on the surface, neutralizing their interactions and reducing the energy required for oxygen vacancy formation. This unique interplay significantly enhances the ORR performance of the Mn-doped double perovskite/Cg composite. The Mn doping approach effectively regulates Lewis acid-base interactions, lowers oxygen vacancy formation energy, and engineers the electronic structure, thereby synergistically accelerating the oxygen reduction reaction. © 2025 Elsevier B.V., All rights reserved.