In Situ Construction of Co/CoS Nanoparticles Embedded in N-Doped Carbon Matrix from Thiophene-Based MOF for Oxygen Evolution Reaction

As a major kinetic bottleneck in electrohydrochemical energy conversion devices, the oxygen evolution reaction (OER) underscores the great significance of developing efficient non-noble metal electrocatalysts. For the purpose of this research, a Co-TDC-dpyb MOF precursor was synthesized, where thiophene-2,5-dicarboxylic acid (H2TDC) and N,N′-bis(3-pyridinecarboxamide)-1,4-butane (3-dpyb) functioned as the dual organic ligands. Through low-temperature pyrolysis, the ligands undergo carbonization to form a nitrogen-doped carbon matrix, while Co2+ ions react in situ with sulfur species released from the thiophene-based ligand, leading to the formation of CoS nanoparticles. The resulting Co/CoS@N–C composite is systematically characterized to elucidate its structural evolution and electrocatalytic mechanism. Electrochemical analyses show that the catalyst outperforms the MOF with an overpotential of only 164.8 mV at a current density of 10 mA cm–2 and a Tafel slope of 131.44 mV dec–1. Moreover, it maintains stable performance over 50 h of continuous operation. The hierarchical structure’s synergistic effects are responsible for the increased OER activity: CoS nanoparticles provide highly active sites, while the nitrogen-doped carbon matrix and metallic Co facilitate electron transfer and structural stability. This work offers a reproducible design strategy for MOF-derived electrocatalysts, accelerating the reasonable advancement of efficient nonprecious metal-based catalysts tailored for energy conversion.