Co-POM@MOF-derivatives with trace cobalt content for highly efficient oxygen reduction

A simple and effective method for constructing highly efficient oxygen reduction catalysts with trace amount of isolated cobalt was firstly developed by the pyrolysis of Co-centered [email protected] framework ([email protected]). The Co-centered polyoxometalate ([CoW12O40]6−) was confined in the well-defined void space of ZIF-8 to achieve homogeneous dispersion of polyoxoanions, where the isolated Co centers were well surrounded by the W-O shell and ZIF-8 framework. The [email protected] N-doping porous carbon (Co-W-NC) with trace cobalt content was facilely prepared by the pyrolysis of the [email protected] under Ar atmosphere. The single dispersion of polyoxoanions in the metal-organic framework with complete separation of Co center surrounding by W-O shell and ZIF-8 framework ensures the uniform dispersion of Co atoms, confirmed by the Fourier transform extended X-ray absorption fine structure measurement. The Co-W-NC composite catalysts exhibit high performance for oxygen reduction reactions with a half-wave potential of 0.835 V in 0.1 mol/L KOH solution with excellent durability, which is much superior to that of the control samples derived from the [PW12O40]@ZIF-8, and the commercial Pt/C. This work highlights a new insight for constructing highly efficient catalysts via the introduction of metal-centered polyoxometalate into metal-organic framework following the high temperature treatment process.