Synthesis of a Paddlewheel-Based 3D Co-MOF and Its Co₃Se₄-Derived Composite as an Electrocatalyst for Water Oxidation

Cobalt selenides, such as Co₃Se₄, are promising electrocatalysts for the oxygen evolution reaction (OER), but their synthesis via pyrolysis is hindered by the redox sensitivity of selenium. Here, we report a strategy to overcome this challenge by employing a three-dimensional (3D) metal-organic framework (MOF), [Co₃(BTC)₂(Ade)₂]·DMF·H₂O (Co-BTC-Adenine MOF), as a precursor. The Co-BTC-Adenine MOF, synthesized solvothermally, featured a paddlewheel-type network with one-dimensional (1D) channels and was characterized by single-crystal X-ray diffraction (SCXRD), powder X-ray diffraction (PXRD), and thermogravimetric analysis (TGA). Upon pyrolysis at 600 °C, a Co₃Se₄-based composite (Co₃Se₄@600) embedded in an N-doped carbon matrix was obtained. This composite exhibited a low overpotential of 235 mV at 10 mA cm^-2, a Tafel slope of 61 mV dec^-1, and excellent durability for over 68 h in alkaline media. The enhanced OER performance is attributed to the porous hybrid architecture, improved conductivity, and synergistic interactions between Co₃Se₄ and the carbon support. This work presented a temperature-controlled route for fabricating robust, nonprecious OER electrocatalysts from MOF precursors.