Dendritic growth of monolayer ternary WS_2(1-x)Se_2x flakes for enhanced hydrogen evolution reaction

Two-dimensional transition-metal dichalcogenides (TMDs) have attracted much research interest in the hydrogen evolution reaction (HER) due to their superior electrocatalytic properties. Beyond binary TMDs, ternary TMD alloys, as electrocatalysts, were also gradually acknowledged for their remarkable efficiency in HER. Herein, we successfully synthesized monolayer dendritic ternary WS_2(1-x)Se_2x flakes possessing abundant active edge sites on a single crystalline SrTiO₃ (STO(100)). And the obtained dendritic WS_2(1-x)Se_2x flakes could be transferred intact to arbitrary substrates, for example, SiO₂/Si and Au foils. Intriguingly, the transferred dendritic WS_2(1-x)Se_2x flakes on Au foil demonstrate a significant HER performance, reflected by a rather lower Tafel slope of ∼69 mV dec^-1 and a much higher exchange current density of ∼50.1 μA cm^-2 outshining other CVD-grown two-dimensional TMD flakes. Furthermore, our new material shows excellent stability in electro-catalyzing the HER, suggestive of its robustness for being an excellent electrocatalyst. We believe that this work broadens the outlook for the synthesis of two-dimensional TMDs toward satisfying the applications in electrocatalysis.