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 Co₃O₄/CeO₂ heterostructure in situ embedded in N-doped carbon nanofibers (h-Co₃O₄/CeO₂@N-CNFs) as a high-performance electrocatalyst for the OER. Unlike previously reported Co₃O₄/CeO₂ composites, the as-prepared Co₃O₄/CeO₂ heterostructure presents hollow and porous features. The nanopores can develop within Co₃O₄/CeO₂ nanocrystals with an analogous mechanism to void formation in the Kirkendall effect. Electrochemical measurements demonstrate that h-Co₃O₄/CeO₂@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 RuO₂ catalyst. The outstanding OER performance originates from the important synergies by combining hollow Co₃O₄/CeO₂ heterostructures and three-dimensional porous N-CNF networks.