Enhancing the electrocatalytic oxygen reduction activity of PrFeO₃ through B-site manganese substitution

The advancement of effective rare-earth-dominated perovskites as electrocatalysts for the Oxygen Reduction Reaction (ORR) holds significant relevance for energy storage systems, such as fuel cells. In this study, we present a simple method to improve the electrocatalytic performance of PrFe_1-x Mn _x O₃ (x = 0.1, 0.2, and 0.3), referred to as PFMO-0.1, PFMO-0.2, and PFMO-0.3, respectively, which are produced using the sol-gel technique. The structural characteristics and morphology of the synthesized materials were thoroughly investigated using XRD, FESEM, TEM, EDS, and XPS. The material characterization indicates that PFMO-0.1 possesses a greater particle size and an increased number of oxygen vacancies, which are advantageous for ORR. The results were verified by testing the electrocatalytic activity using a rotating disk electrode (RDE) and a rotating ring disk electrode (RRDE) in 0.1 M KOH. PFMO-0.1 exhibited the highest onset potential of 0.76 V vs. RHE, a notable limiting current of -3.64 mA cm^-2, and a superb half-wave potential E _1/2 = 0.59 V vs. RHE. The electron transfer number (n), calculated from a RRDE, is nearly equal to 4. The PFMO-0.1 catalyst's superior catalytic performance is further supported by its diminished Tafel slope, which indicates faster reaction kinetics for the ORR. Furthermore, chronoamperometric studies validated that the PFMO-0.1 electrocatalyst demonstrates greater longevity and improved methanol-resistant performance in relation to the standard commercial Pt/C catalyst.