Intercalation of cobaltocene into WS2 nanosheets for enhanced catalytic hydrogen evolution reaction

Abstract

We synthesized cobaltocene (7–20%)-intercalated WS₂ nanosheets using a solvothermal process. The intercalation of cobaltocene between the expanded 1T′ phase WS₂ layers was confirmed by scanning transmission electron microscopy and electron energy loss spectroscopy. The intercalated complexes exhibited excellent performance for the catalytic hydrogen evolution reaction, with a Tafel slope of 40 mV dec⁻¹ and a current density of 10 mA cm⁻² at 0.17 V (vs. RHE). Spin-polarized density functional theory calculations showed that cobaltocene is intercalated with a fivefold symmetry parallel to the WS₂ plane, driven by substantial charge transfer. Reaction pathway calculations suggest that the basal S atoms just above the Co atom are the active sites, and the activation barrier of the Heyrovsky reaction determines the catalytic activity.