Hollow Co₃O₄/CeO₂ Heterostructures in Situ Embedded in N-Doped Carbon Nanofibers Enable Outstanding Oxygen Evolution

Exploring highly efficient and cost-effective electrocatalysts with more feasible synthesis strategies toward oxygen evolution reaction (OER) is highly desirable for a broad range of advanced sustainable energy conversion systems. Herein, we develop a feasible electrospinning strategy for the facile fabrication of a Co 3 O 4 /CeO 2 heterostructure in situ embedded in N-doped carbon nanofibers (h-Co 3 O 4 /CeO 2 @N-CNFs) as a high-performance electrocatalyst for the OER. Unlike previously reported Co 3 O 4 /CeO 2 composites, the as-prepared Co 3 O 4 /CeO 2 heterostructure presents hollow and porous features. The nanopores can develop within Co 3 O 4 /CeO 2 nanocrystals with an analogous mechanism to void formation in the Kirkendall effect. Electrochemical measurements demonstrate that h-Co 3 O 4 /CeO 2 @N-CNFs can enable high OER activity with a low overpotential of 310 mV to achieve 10 mA cm –2 current density and good stability that can maintain 40 000 s without perceptible attenuation, outperforming those of the commercial RuO 2 catalyst. The outstanding OER performance originates from the important synergies by combining hollow Co 3 O 4 /CeO 2 heterostructures and three-dimensional porous N-CNF networks.