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

Abstract 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 ≈5% 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.