γ-Fe2O3 clusters embedded in 1D porous N-doped carbon matrix as pH-universal electrocatalyst for enhanced oxygen reduction reaction

Carbon-based materials have shown promising results in replacing commercial Pt/C as highly efficient oxygen reduction reaction (ORR) catalysts in renewable energy devices. Designing unique structures of carbon matrix and introducing more active sites are essential for their application as electrode materials. Herein, a feasible approach is reported to synthesize dispersive γ -Fe 2 O 3 clusters embedded in 1D porous carbon nanofibers (CNFs) ( γ -Fe 2 O 3 @CNFs-12) through electrospinning, impregnation and pyrolysis processes. The resulted γ -Fe 2 O 3 @CNFs-12 exhibits excellent ORR performance in alkaline electrolyte with a surprising half-wave potential ( E 1/2 ) of 0.905 V and merely 5 mV drop of the potential after 5000 cycles, outperforming that of commercial Pt/C. Meanwhile, it also shows considerable ORR performance in acidic and neutral media. The remarkable ORR catalytic activity and durability are primarily attributable to the well-designed 1D hierarchical porous structure and accessible γ -Fe 2 O 3 clusters that embedded in carbon nanofibers. γ -Fe 2 O 3 @CNFs-12 is also capable to act as an air cathode for Zn-air batteries with an open circuit voltage of 1.428 V. This work provides a new perspective to the novel design and synthesis of carbon-based ORR electrocatalysts.