Fe3O4/FeS2 Heterostructures Enable Efficient Oxygen Evolution Reaction
Although Fe has been occasionally recognized to be the active site in electrochemical oxygen evolution reaction (OER), monometallic Fe based catalysts still demonstrate insufficient OER activity in comparison to the monometallic Ni and combined Fe-Ni materials. Herein, we report a highly active monometallic Fe catalyst by constructing the Fe3O4/FeS2 heterostructures. Particularly, an in-situ sulfuration route leads to a series of heterostructured Fe3O4/FeS2 materials which own tunable sulfuration degrees and variable contents of heterogeneous interfaces. In OER conducted in an alkaline system, the acquired Fe3O4/FeS2-2.5 catalyst with the most abundant hetero-interfaces, exhibits superior performance by giving ultralow overpotentials and nice durabilities. Density functional theory computation reveals that charge redistribution at the interface region decreases the activation barrier for forming oxygen-containing intermediates which greatly accelerates the sluggish OER kinetics. This work clarifies that monometallic Fe based material can deliver a high OER activity, and Fe should be an actural active site in this reaction. Besides, constructing the anion species-different heterogeneous structure which received few attention before, may represent a promisting strategy for designing highly active monometallic catalysts.