Enhanced Catalytic Activities of Surfactant-Assisted Exfoliated WS₂ Nanodots for Hydrogen Evolution.

WS2 nanodots were prepared by liquid-phase exfoliation of bulk WS2 crystals in surfactant aqueous solution with the aid of ultrasonication. Their behaviors on catalyzing hydrogen evolution reaction (HER) were investigated after drop-casting them onto a glass carbon electrode. On the basis of the optical and electron characterizations, the nanodots were identified with a high concentration of octahedral phase of WS2 that showed better catalysis properties than the hexagonal WS2. From the polarization curve, the Tafel slope was estimated to be 51 mV per decade and the onset potential was 90 mV, indicating good catalytic performance of such nanodots. Our results suggest that surfactant-mediated exfoliation is an environmentally benign method to synthesize WS2 nanodots for improved catalyzing HER.