Dendritic, Transferable, Strictly Monolayer MoS₂ Flakes Synthesized on SrTiO₃ Single Crystals for Efficient Electrocatalytic Applications

Abstract

Controllable synthesis of macroscopically uniform, high-quality monolayer MoS₂ is crucial for harnessing its great potential in optoelectronics, electrocatalysis, and energy storage. To date, triangular MoS₂ single crystals or their polycrystalline aggregates have been synthesized on insulating substrates of SiO₂/Si, mica, sapphire, <i>etc.</i>, <i>via</i> portable chemical vapor deposition methods. Herein, we report a controllable synthesis of dendritic, strictly monolayer MoS₂ flakes possessing tunable degrees of fractal shape on a specific insulator, SrTiO₃. Interestingly, the dendritic monolayer MoS₂, 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 MoS₂ flakes. In addition, we reveal that centimeter-scale uniform, strictly monolayer MoS₂ films consisting of relatively compact domains can also be obtained, offering insights into promising applications such as flexible energy conversion/harvesting and optoelectronics