Co(II)-salen complex encapsulated into MIL-100(Cr) for electrocatalytic reduction of oxygen

Co(II)-salen was encapsulated in MIL-100(Cr) metal organic framework by “ship in a bottle” to synthesize a new electrocatalyst, Cosalen@MIL100(Cr). The material was characterized by XRD, FT-IR, UV-Vis and N₂-adsorption. The Cosalen@MIL-100(Cr) modified glassy carbon electrode exhibits a well-defined reduction peak at the potential of −0.21 V toward the oxygen reduction reaction (ORR) by cyclic voltammetry (CV) in pH = 6.84 phosphate buffer. Almost 400 mV positive shift of potential at Cosalen@MIL-100(Cr) modified electrode for ORR compared with that at bare glassy carbon, indicates that Cosalen@MIL-100(Cr) possesses excellent electrocatalytic activity. The transferred number of electrons for ORR was determined by chronocoulometry. The result suggests that the introduction of Co(II)-salen complex into MOF increases the electrocatalytic activity via a four-electron reduction pathway. Furthermore, this electrocatalyst exhibits good stability and reproducibility.