Fe, S-uniformly dispersed Ni MOFs based on FeS substrate precipitation-dissolution equilibrium for water and seawater oxidation

In the pursuit of advancing electrocatalysts for the alkaline oxygen evolution reaction (OER), the development of nickel-based metal-organic frameworks (MOFs) with a judicious balance of cost-effectiveness and catalytic efficacy is of paramount importance. Herein, we have achieved a commendable feat in the synthesis of Ni MOFs integrated with uniformly dispersed Fe and S species on a FeS substrate based on the precipitation-dissolution equilibrium. For the obtained Ni MOFs/FeS/IF catalyst, three factors including excellent conductivity of FeS substrate, conjugated carboxylate ligands and spindle-shaped structure with uniformly dispersed Fe and S can contribute to the enhanced activity for OER. The electrochemical measurements show that Ni MOFs/FeS/IF requires overpotentials of 250 and 280 mV to reach current densities of 100 mA cm-2 in 1 M KOH and 1 M KOH seawater, respectively, as compared to that (427@100 mA cm-2 in 1 M KOH, 455@100 mA cm-2 in 1 M KOH seawater) of Ni MOFs/NF. Interestingly, the Ni MOFs/FeS/IF electrode displayed remarkable electrochemical stability with a high current density of 500 mA cm-2 after testing for 50 h, which is attributed to the synergistic effect of the bimetallic centers and optimized coordination environments via Ni-S bonds. The study reveals the potential for efficiently driving freshwater and seawater splitting by uniformly distributing anions and cations based on the precipitation-dissolution equilibrium during the in situ generation of metal-organic frameworks toward advanced electrocatalysts. In the pursuit of advancing electrocatalysts for alkaline oxygen evolution reaction (OER), the development of nickel-based metal-organic frameworks with a judicious balance of cost-effectiveness and catalytic efficacy is of paramount importance.