Utilizing Surfactant for Size Control: Fabricating Highly Dispersed Nanoscale Fe3o4 Electrocatalysts with Enhanced Performance for Oxygen Reduction Reaction and Zn-Air Battery

Abstract

This study presents a method to synthesize Fe3O4 nanoparticles with controlled morphology and enhanced electrocatalytic performance. FeSO4·7H2O, NaOH, and 1,4,5,8-naphthalene tetracarboxylic dianhydride were utilized as precursors, while the addition of sodium dodecyl sulfate (SDS) as a surfactant allowed for precise control over particle size and shape. The gradual increase in SDS concentration led to a transformation from large irregular particles (S0-Fe3O4: 100-500 nm) to well-dispersed, uniform nanoparticles (S2-Fe3O4: 20-30 nm) that exposed a high density of active sites. S2-Fe3O4 exhibited significantly enhanced electrocatalytic performance compared to the SDS-free S0-Fe3O4, with a remarkable limiting diffusion current density (-4.78 mA cm-2) approaching that of 20% Pt/C (-5.60 mA cm-2). Density functional theory calculations further confirmed the similarity between the reaction barriers (0.64 eV and 0.61 eV) of S2-Fe3O4 and Pt (111) (0.40 eV), indicating the potential of Fe3O4 as a promising alternative to Pt-based catalysts. Moreover, the utilization of S2-Fe3O4 in a Zn-air battery resulted in an open circuit voltage of -1.33 V, effectively powering an LED light source. This study paves the way for the development of high-performance electrocatalysts, offering a viable substitute to traditional Pt-based catalysts in various energy conversion and storage applications.

Keywords: Fe3O4, sodium dodecyl sulfate, catalyst, oxygen reduction reaction, fuel cell, Zn-air battery.