0D–2D Schottky heterostructure coupling of FeS nanosheets and Co₉S₈ nanoparticles for long-term industrial-level water oxidation

The effective electron and interface/structural coupling for heterostructure electrocatalyst is the key to regulating the intrinsic activity and stability for oxygen evolution reaction (OER). Herein, a facile strategy is developed to fabricate well-dispersed zero-dimensional (0D) metallic Co₉S₈ nanoparticles on two-dimensional (2D) FeS nanosheets, forming FeS-Co₉S₈ Schottky heterostructures with abundant heterointerfaces as OER electrocatalyst. The strong electronic coupling between FeS and Co₉S₈ expedites electrons flow from Fe atoms in FeS nanosheets to Co atoms in tetrahedron sites (Co_Td), thereby leading to the structural integrity of the heterostructure and the constant exposure of active sites. Operando Raman spectroscopy also indicates the Co sites in the FeS-Co₉S₈ Schottky heterostructure are OER active sites. Therefore, FeS-Co₉S₈ heterostructure supported by iron foam (FeS-Co₉S₈/IF) shows the remarkable activity and durability, achieving an industrial-level 500 mA·cm⁻² current density at an overpotential of only 332 mV and maintaining for 100 h. This work demonstrates that constructing Schottky heterostructure interface with strong coupling effect may be a good strategy for excellent catalytic performances.