Intercalation of cobaltocene into WS2 nanosheets for enhanced catalytic hydrogen evolution reaction†
Abstract
We synthesized cobaltocene (7â20%)-intercalated WS2 nanosheets using a solvothermal process. The intercalation of cobaltocene between the expanded 1Tâ² 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 decâ1 and a current density of 10 mA cmâ2 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.