Production of N-doped Reduced Graphene Oxide/Fe3O4 Hybrids and Effect of Order of Production Steps on Electrocatalytic Performances for Oxygen Reduction Reaction

초록

Oxygen reduction reactions (ORRs) occur at cathodes in fuel cells and require efficient electrocatalysts. Because of the cost and limited durability and stability of commercial Pt/C catalysts, the development of efficient Pt-free electrocatalysts is an active research topic. Here, we describe the solution-based production of Fe3O4 nanoparticles/N-doped graphene-based materials from FeCl2, graphene oxide (G-O), and hydrazine. Orders of production steps were varied by; i) reacting FeCl2 and G-O first and then adding hydrazine (Fe/G-N), ii) reacting G-O, FeCl2, and hydrazine at the same time (Fe/G/N), or iii) reacting G-O and hydrazine first and then adding FeCl2 (G/N-Fe). The hybrids produced showed better ORR electrocatalytic activity in alkaline media than single components such as N-doped graphene-based materials or Fe3O4. Furthermore, the electrocatalytic properties of the resulting hybrids were found to depend on orders of addition. Fe/G/N was found to be the best electrocatalyst and had better onset and half-wave potentials, thermodynamic current density, and 4-electron selectivity. All three hybrids show good cyclic durability and methanol tolerance.

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