Polyoxometalates metal-organic frameworks-derived transition metal sulfides with rich interfaces for efficient alkaline oxygen evolution reaction.

Designing a highly coupled interfacial-engineered transition metal sulfide electrocatalyst with rich interfaces is crucial for accelerating the catalytic oxygen evolution reaction (OER), which involves several intermediates. This study presents a novel polyoxometalate-based metal-organic framework (POM-MOF)-derived Fe- and Mo-codoped NiS/Ni9S8 heterostructure supported on a nickel foam (NF) (denoted as Fe,Mo-NiS/Ni9S8/NF). The newly prepared Fe,Mo-NiS/Ni9S8/NF catalyst possesses rich interfaces of NiS and Ni9S8 with uniformly doped Fe and Mo atoms. The optimized Fe,Mo-NiS/Ni9S8/NF catalyst demonstrated best OER performance with ultralow overpotentials of 47 and 56 mV at 10 mA·cm-2 for alkaline and simulated seawater, respectively. This resulting performance is attributed to its low interfacial resistance, fully exposed active sites, superhydrophilic properties, and excellent electronic interactions. Furthermore, Fe,Mo-NiS/Ni9S8/NF exhibited strong durability under both alkaline and simulated seawater conditions for 100 h, fulfilling the requirements of an effective water oxidation electrocatalyst. This study focused on the design and optimization of POM-MOF sulfide derivatives for electrocatalytic OER, offering broadened avenues for the application of POM-MOF-derived heterostructures in renewable energy conversion and storage.