Improving the electrocatalytic activity of NiFe bimetal-organic framework toward oxygen evolution reaction by Zr doping

Highly efficient electrocatalysts for the oxygen evolution reaction (OER) are strongly desired in oxygen involved technologies such as water splitting and metal-air batteries. Recently, metal organic frames (MOFs) have become one kind of OER electrocatalysts. To obtain MOFs with high OER activity, the ternary NiFeZr MOFs were synthesized and prepared by a simple solvothermal method. The results show that the OER performance of ternary NiFeZr MOFs is better than the corresponding bimetallic NiFe MOFs due to the doping of Zr. At the optimal dosage of Zr of 0.12 mmol, the overpotential at 10 mA/cm2 (η10) of NiFeZr MOFs-0.12 on the glass carbon electrode is only 288 mV. The reasons behind were explored from the aspects of electrochemical surface area (ECSA), electrochemical impedance spectroscopy (EIS), electronic structure and zeta potential of catalysts and the OER mechanism on NiFeZr MOFs was also revealed. To further improve the OER activity, the NiFeZr MOFs-0.12 was grown in-situ on the nickel foam (NF), which exhibits an overpotential at 50 mA/cm2 (η50) of only 345 mV and good stability. This study proves that the reasonable incorporation of metal into OER active MOFs is effective to improve their OER activity.