Nanorod-like NiFe metal-organic frameworks for oxygen evolution in alkaline seawater media

Searching for highly active and durable oxygen evolution reaction (OER) electrocatalysts is the key to break through the bottleneck of overall water splitting. Here, we prepare NixFe-BDC (H2BDC = terephthalic acid) nanorods with different Ni/Fe ratios by a facile solvothermal method for the OER. The optimal Ni3Fe-BDC exhibits a low overpotential (η10) of 265 mV and a Tafel slope of 90 mV·dec−1 in 1 M KOH. Moreover, it shows a low η10 of 280 mV and excellent stability in the mixture of 1 M NaCl and 1 M KOH, which has strong corrosion resistance to Cl− anions. The role of Fe3+ not only increases the charge transfer rate of Ni3Fe-BDC, but also affects the specific surface area of the catalyst with high electrochemical activity. Kinetic studies show that both Fe and Ni sites act as active centers, which catalyze synergistically to reduce the reaction kinetic energy barrier. Characterization results of the used Ni3Fe-BDC reveal that the in situ formed rod-like Ni3FeOOH is the active site for the OER.