Cobalt oxide/cerium oxide/carbon heterostructure nanoflowers derived from CoCe-ZIF-67 as efficient electrocatalyst for oxygen evolution reaction

Efficient oxygen evolution reaction (OER) electrocatalysts with non-noble metals are very important for the large-scale application of electrocatalytic hydrogen production systems. ZIF-67 as a promising precursor to prepare Co-based catalysts suffer from its poor conductivities and low intrinsic catalytic activities. In this study, we developed a Co₃O₄/CeO₂/C heterostructure nanoflowers (CoCe/C HFs) catalyst with two-dimension (2D) nanostructures using a facile one step hydrothermal reaction. This method is both energy-efficient and environmentally friendly. Hierarchical three-dimensional (3D) nanoflower structure increased active metal sites enhanced the electronic conductivity. The synthesized Co₁₀Ce₁/C HFs (the molar ratio of Co:Ce = 10:1) display excellent OER activities with a low overpotential of 274 mV and small Tafel slope (82.6 mV dec⁻¹) in 1 M KOH. This performance surpasses that of both monometallic Co₃O₄/C and the commercial RuO₂ catalysts. Electrochemical tests, X-ray photoelectron spectroscopy, and density functional theory (DFT) calculations results indicate that the superior OER performance of Co₁₀Ce₁/C HFs is attributed to optimized electronic structure of Co₃O₄, and the improved conductivities and the cooperative effects between Co₃O₄ and CeO₂ interfaces.