Enhanced electrocatalytic activity of Pt decorated spinals (M3O4, M = Mn, Fe, Co)/C for oxygen reduction reaction in PEM fuel cell and their evaluation by hydrodynamic techniques

Abstract

This work aims to study the contribution of Mn, Fe and Co based spinal oxides in enhancement of fuel cell performance by decorating them with Pt nano particles via polyol reduction method. Mn, Fe and Co based spinal oxides were synthesized by co-precipitation method followed by sintering at high temperature. The structural properties of carbon supported Pt decorated spinal oxides (Mn3O4, Fe3O4, Co3O4) were analyzed by XRD, HRTEM with EDX while their electrochemical properties were analyzed by cyclic voltammetry and hydro dynamic linear sweep voltammetry (RDE, RRDE) techniques. Accelerated durability test (ADT) was carried out to assess the stability of electrocatalysts and then single cell was assembled and polarized from open circuit potential to zero potential. The XRD results reveal the crystalline nature of Mn3O4, Fe3O4 and Co3O4 oxides as well as the Pt decoration on the surface of these spinal oxides. HR-TEM images clearly illustrate the decoration of the surface of spinal oxides by Pt particles of about 2–4nm. Presence of the elements, Mn, Fe, Co, Pt and O were confirmed by EDAX analysis. The electrochemical surface area (ECSA) of Pt-Mn3O4/C is 135.3m2g−1 Pt which is more than twice of Pt/C. Pt-M3O4/C (Mn, Fe, Co) electrocatalysts follow four electron transfer mechanism in oxygen reduction reaction (ORR). Pt-Mn3O4/C reveals 6.8 times higher mass activity than Pt/C and their specific activity is around 3.7 times higher than Pt/C. Single cell polarization of Pt-M3O4/C (M=Mn, Fe, Co) cathodes showed a maximum power density of 761, 727 and 699mWcm−2 respectively at 80°C. This work demonstrates Mn3O4, Fe3O4 and Co3O4 oxides decorated with Pt as efficient electrocatalysts in oxygen reduction reaction process.