Template‐Assisted Synthesis of Metallic 1T′‐Sn0.3W0.7S2 Nanosheets for Hydrogen Evolution Reaction

Crystal phase control still remains a challenge for the precise synthesis of 2D layered metal dichalcogenide (LMD) materials. The T′ phase structure has profound influences on enhancing electrical conductivity, increasing active sites, and improving intrinsic catalytic activity, which are urgently needed for enhancing hydrogen evolution reaction (HER) activity. Theoretical calculations suggest that metastable T′ phase 2D Sn1−xWxS2 alloys can be formed by combining W with 1T tin disulfide (SnS2) as a template to achieve a semiconductor‐to‐metallic transition. Herein, 2D Sn1−xWxS2 alloys with varying x are prepared by adjusting the molar ratio of reactants via hydrothermal synthesis, among which Sn0.3W0.7S2 displays a maximum of concentration of 81% in the metallic phase and features a distorted octahedral‐coordinated metastable 1T′ phase structure. The obtained 1T′‐Sn0.3W0.7S2 has high intrinsic electrical conductivity, lattice distortion, and defects, showing a prominently improved HER catalytic performance. Metallic Sn0.3W0.7S2 coupled with carbon black exhibits at least a 215‐fold improvement compared to pristine SnS2. It has excellent long‐term durability and HER activity. This work reveals a general phase transition strategy by using T phase materials as templates and merging heteroatoms to achieve synthetic metastable phase 2D LMDs that have a significantly improved HER catalytic performance. Sn1−xWxS2 alloys are synthesized with 1T SnS2 as the template by adjusting the molar ratios of the precursors. The Sn0.3W0.7S2 alloy shows up to 83% metallic properties and possess a distorted octahedral coordination 1T′ phase structure. Metallic 1T′‐Sn0.3W0.7S2 endows a markedly enhanced hydrogen evolution reaction (HER) performance. The auxiliary of carbon black further effectively improves HER, catalytic performance rarely attenuates, and structure morphology remains stable.