Combined MOF derivation and fluorination imparted efficient synergism of Fe-Co fluoride for oxygen evolution reaction

Abstract

Novel and efficient MOF derivatives are significant to high-performance catalyst fabrication and application. By combining the MOF derivation and fluorination approaches, herein, we demonstrated an efficient catalyst of ZIF-FeCo MOFs derived FeCo fluoride hybrid with efficient catalytic synergism for electrochemical oxygen evolution reaction (OER). The temperature dependence of fluorination for derivatives is observed by the physical characterization and electrochemical measurements. The optimal catalysts show the best catalytic performance for OER with 250 mV overpotentials (No IR correction) to offer 10 mA cm−2 loaded on glass carbon electrode, which is much better than that of the pristine ZIF-FeCo MOFs and the traditional carbonization derivatives of ZIF-FeCo/C. An efficient synergism of Fe and Co in the catalyst system is demonstrated compared to the single metal MOF-derived fluorides. The specific activity and TOF value at 1.53 V are 2.34 mA cm−2 and 0.055 s−1, respectively, about 17 and 55 times higher than the pristine ZIF-FeCo MOF, and 5 and 14 times higher of ZIF-FeCo/C samples. High catalytic performances of catalytic stability, kinetics, charge transfer ability and active sites efficiency can be attributed to the combined techniques of MOF derivatives and fluorination etching induced high electrochemical surface area, more active site exposure, conductivity improvement and the facile high valence state of Co active phase formation coming from the high polarity of chemical bonds. The current work expands the application of MOF derivatives in the field of energy conversion and catalysis reactions.