On the synthesis of morphology-controlled transition metal dichalcogenides via chemical vapor deposition for electrochemical hydrogen generation

Shape-engineered atomically thin transition metal dichalcogenide (TMD) crystals are highly intriguing systems with regard to both fundamental and applied science. Herein, a chemical vapor deposition-assisted generalized synthesis strategy for the triangular- and dendritic-shaped TMDs and their ternary alloys is proposed, and the TMD structures' potential for electrocatalytic hydrogen evolution reaction (HER) applications is demonstrated. The alloy formation is confirmed via micro-Raman and photoluminescence studies and further verified using transmission electron microscopy and X-ray photoelectron spectroscopy. The HER activities of MoS ₂ and MoSe ₂ triangles are compared with those of their dendritic structures, and an enormous improvement in terms of overpotential and current density is observed for the dendritic structures. A further enhancement of the HER activity is observed in MoS _2(1−x)Se _2x triangular and dendritic structures, with dendritic MoS _2(1−x)Se _2x providing the best activity. The demonstrated nonequilibrium growth technique opens new avenues for the synthesis of morphology-controlled, large area, complex, and atomically thin TMD structures, which can have unprecedented properties, such as the enormous catalytic activity, tunable luminescence, etc., as presented in this article.