Single-phase Mn-Fe interfacial oxides nanocomposites encored on carbon nitride sheets exhibited enhanced performance for electrocatalytic oxygen reduction reactions

Abstract

• Precious-metal-free cathode catalyst for sustainable energy application developed. • Interfacial binary oxides share single-phase geometry constituting cathode catalyst. • Mn-Fe oxides with carbon nitride synergistically enhanced electrocatalytic ORR. • Developed catalyst exhibited two folds higher ORR activity than commercial Pt/C. The oxygen reduction reactions (ORR) catalysis in fuel cells plays a pivotal role to complete the reactions at the cathode side. The economical low-cost of catalyst is highly required for competing for commercial catalysts with enhanced performance. Herein, we have been successful in developing precious-metal-free catalyst with characteristic features of single-phase interfacial binary Mn and Fe oxides on carbon nitride (Mn-Fe-O/CN) composite material. The performed physical characterizations such as TEM, HRTEM, XRD, Raman and XPS revealed and confirmed the synthesis of the composite material in line with the claimed features. The developed catalyst was tested for oxygen reduction reactions in an acidic medium, and the compared performance with that of commercial 20% wt Pt/C catalyst exhibited enhanced ORR performance with an onset potential of 0.84V vs RHE, which is comparable to that of Pt/C. In addition, the Mn-Fe-O/CN catalyst generated two folds higher current density calculated at 0.90V vs RHE compared with the Pt/C catalyst. The enhanced ORR performance of Mn-Fe-O/CN catalyst may ascribe to the multi-features of composite material, which boosted the simultaneous adsorptions and chemisorptions of oxygen molecules at interfacial binary oxide surface due to electrons transference phenomenon supported by metal-to-support interactions of graphitic carbon nitride intimated sheets.