The structure and catalytic performance for oxygen reduction reaction of worm-like CNTs with Fe3P and Fe0.8Mn0.2 alloy encapsulated

Abstract

Developing transition metal-based catalysts is a feasible approach to decrease the cost of fuel cells. In this paper, we synthesized a worm-like carbon nanotubes (CNTs) encapsulated Fe₃P and Fe_0.8Mn_0.2 alloy based catalysts (FP/FM@CNTs) for oxygen reduction reaction (ORR) by calcination method. The precursor for the calcination was prepared by hydrothermal method. The CNTs encapsulation structure was confirmed by SEM, HRTEM, XRD, XPS and EDS tests. The electrocatalytic performances for ORR of the catalyst were examined in 0.1 M KOH electrolyte by using CV, LSV, Tafel, EIS, RDE and RRDE tests. The obtained results presented that the half-wave potential(E_1/2) of FP/FM@CNTs catalyzed ORR was 0.892 V (vs. RHE), the maximum current intensity and the Tafel slope of FP/FM@CNTs catalyzed ORR were superior to that of the Pt/C catalyst. The density function theory calculation ascertained that the encapsulated Fe₃P made the carbon atoms in surface layer CNT in negative electron state that could transfer electrons easily to oxygen molecular and promote the ORR happening. On the other hand, the CNTs encapsulation structure protected the Fe_0.8Mn_0.2 alloy and Fe₃P from the directly contact with electrolyte and other reactants, which assured the long-term operational stability of the catalysts. The content of this paper presents a novel approach for designing high-performance catalysts.