Synthesis of 2H‐1T′ WS₂‐ReS₂ Heterophase Structures with Atomically Sharp Interface via Hydrogen‐Triggered One‐Pot Growth

Abstract 2D transition metal chalcogenides (TMDs) with different compositions, phase structures, and properties offer giant opportunities for building novel 2D lateral heterostructures. However, the studies to date have been largely limited to homophase TMD heterostructures, while the construction of heterophase TMD heterostructures remains a challenge. Herein, the synthesis of 2H‐1T′ WS₂‐ReS₂ heterophase junctions with high‐quality interface structure via a hydrogen‐triggered one‐pot growth approach is reported. Sequential introduction of hydrogen during growth system, which acts as a “switch” to selectively turn off the growth of ReS₂ while turning on the growth of WS₂, allows WS₂ to seamlessly grow around ReS₂ to form the WS₂‐ReS₂ heterojunction. Moreover, WS₂ prefers to nucleate at the vertices of ReS₂ grain with fixed lattice orientation, which makes the surrounding WS₂ grains merge into single crystal. Scanning transmission electron microscopy reveals high crystal quality of the heterojunction with an atomically sharp 2H‐1T′ heterophase interface. Transient absorption spectroscopy indicates that the photocarriers can effectively separate at the heterophase interface. Based on the high quality heterophase junction, prominent rectification characteristics and polarization‐dependent photodiode properties are achieved. This study provides a robust way for the controlled synthesis of 2D heterophase structures, which is essential for their fundamental studies and device applications.