A novel 3D cobalt-metal organic framework based mixed O/N-donor ligands: Synthesis, structure, and electrochemical OER performance

Abstract

Cobalt metal organic frameworks (Co-MOFs), as promising potential electrocatalyst materials, have been extensively investigated owing to high catalytic active center, uniform catalytic site, large specific surface area, adjustable pore. A new Co-MOF, namely, {[Co2(L)(4,4′-bbibp)2]·4(H2O)}n [YMUN 9 (YMUN for Youjiang Medical University for Nationalities)], has been synthesized based on semi-rigid dicarboxylic acid and rigid imidazole ligands (H2L = 3,5-bis(3,5-dicarboxylphenoxy)benzoic acid, 4,4′-bbibp = 4,4′-bis(benzimidazol-1-yl)biphenyl). YMUN 9 displays a 3D framework through by means of single-crystal X-ray diffraction (SC-XRD). In order to present the structure more clearly, YMUN 9 can be defined as a 3D 2-nodal (4,4)-connected network with the point symbol of {4·85}2{42·104} through topology analysis. YMUN 9-D has been obtained based on YMUN 9 through a new strategy that of programmed heat treatment of YMUN 9. The oxygen evolution reaction (OER) electrochemical activity of YMUN 9-D has been investigated through cyclic voltammetry (CV), linear scanning voltammetry (LSV), chronopotentiometry (CP), and electrochemical impedance spectroscopy (EIS), in 0.1 M KOH electrolyte. The investigated results revealing that YMUN 9-D has a prominent overpotential of 273.9 mV (at J = 10 mA·cm−2), and keeps great chemical stability until 1000 mins. The Tafel slope of YMUN 9-D is 141.9 mV·dec−1 and its double layer capacitance is found to be 32 mF·cm−2. Compared to other MOFs materials, YMUN 9-D displays similar or superior electrocatalytic performance.