Robust Synthesis of Large-Area PtSe₂ Microbelts by Step-Induced Separation Growth on Au(001) Substrate for The Hydrogen Evolution Reaction

Platinum selenide (PtSe2), an emerging 2D material, has attracted extensive attention owing to its wide-tunable bandgap and ultrahigh conductivity for potential applications in optoelectronic and energy devices. However, the preparation of atomically thin PtSe2 remains a big challenge due to its large formation energy. Herein, the robust synthesis of large-area ultrathin PtSe2 microbelts via a step-induced separation growth strategy on Au(001) substrate is demonstrated. Thanks to the high controllability of this approach, the continuous modulation of the thickness of PtSe2 microbelts from monolayer to bulk is realized and the sample coverage from approximate to 5% to approximate to 100% by coordinately tuning the growth temperature and time. Theory calculations indicate that the significant reduction of formation energy of PtSe2 nucleation at the Au steps, along with the high-efficiency separation-supply of Pt precursor, are responsible for the robust synthesis of PtSe2. Owing to the rich-edges with abundant active sites and metallic conduction features of ultrathin PtSe2 microbelt, it can act as an excellent electrocatalyst, featured with a record high hydrogen evolution reaction efficiency (Tafel slope: 37 mV dec(-1)). This work provides new insights into the highly efficient synthesis of large-scale 2D materials for exploring their unique physics and fascinating applications.