Engineering Single‐Layer Hollow Structure of Transition Metal Dichalcogenides with High 1T‐Phase Purity for Hydrogen Evolution Reaction

Abstract Rational design and controllable synthesis of hollow structures based on transition metal dichalcogenides (TMDs) have gained tremendous attention in the field of clean energy. However, the general synthetic strategies to fabricate single‐layer hollow structures of TMDs, especially with unconventional phases (e.g., 1T or 1T′), still pose significant challenges. Herein, a scalable method is reported for the synthesis of single‐layer hollow spheres (SLHS) of TMDs with high 1T‐phase purity by etching bismuth (Bi) cores from pre‐synthesized Bi@TMDs core–shell heterostructures including SLHS‐1T‐MoS₂, SLHS‐1T‐MoSe₂, SLHS‐1T‐WS₂, and SLHS‐1T‐WSe₂. Additionally, the etched Bi ions can be adsorbed on the single‐layer TMDs shells in the form of single atoms (SAs) via the Bi─S bond. Due to the benefits of the single‐layer hollow structure, high conductivity of 1T phase, and synergistic effect of Bi SAs and TMDs supports, the fabricated SLHS‐1T‐MoS₂ exhibits superior electrocatalytic performance for hydrogen production. This work provides a way to manufacture advanced functional materials based on the single‐layer hollow structures of 1T‐TMDs and to expand their applications.