Dendritic, Transferable, Strictly Monolayer MoS_2 Flakes Synthesized on SrTiO3 Single Crystals for Efficient Electrocatalytic Applications

摘要

Controllable synthesis of macroscopically uniform, high-quality monolayer MoS_2 is crucial for harnessing its great potential in optoelectronics, electrocatalysis, and energy storage. To date, triangular MoS_2 single crystals or their polycrystalline aggregates have been synthesized on insulating substrates of SiO2/Si, mica, sapphire, etc., via portable chemical vapor deposition methods. Herein, we report a controllable synthesis of dendritic, strictly monolayer MoS_2 flakes possessing tunable degrees of fractal shape on a specific insulator, SrTiO3. Interestingly, the dendritic monolayer MoS_2, characterized by abundant edges, can be transferred intact onto Au foil electrodes and serve as ideal electrocatalysts for hydrogen evolution reaction, reflected by a rather low Tafel slope of～73 mV/decade among CVD-grown two-dimensional MoS_2 flakes. In addition, we reveal that centimeter-scale uniform, strictly monolayer MoS_2 films consisting of relatively compact domains can also be obtained, offering insights into promising applications such as flexible energy conversion/harvesting and optoelectronics.