Iron single Atom–Iron nanoparticles dual-deposited nitrogen-doped graphene hybrid as an innovative catalyst to enhance the oxygen reduction reaction

The fabrication of an effective electrocatalyst for cathodic oxygen reduction reaction (ORR) is important to enhance the performance of fuel cell applications. Here, we prepared a novel hybrid material based on the combination of iron single atoms–small iron nanoparticles homogeneously distributed on the surface of nitrogen-doped graphene nanosheets (Fe_SA-Fe_NPs/NG). The achieved Fe_SA–Fe_NPs/NG material exhibited high catalytic ORR behaviors with high positive values of +0.94 V and +0.81 V for onset potential and half-wave potential, respectively, as well as the remarkable stability with 90% retention of initial current over an operation period of 15 000 s), superior to commercial Pt/C in 0.1 M KOH medium. In addition, the material favored a four-electron reaction pathway along with good methanol crossover tolerance towards ORR. The outstanding catalytic performance could be attributed to the formation of a unique microporous nanoarchitecture owning large specific surface area of 103.63 m² g⁻¹ and high conductivity, which create rich active sites and fast charge transfer ability, thus effectively accelerating the adsorption and catalyzation processes to convert oxygen reactant to product during ORR. These findings suggest a novel route for the synthesis of potential catalysts exhibiting excellent efficiency and cost effectiveness for fuel cell industries.