The Controllable Synthesis of High‐Quality Two‐Dimensional Iron Sulfide with Specific Phases

Abstract 2D Fe‐chalcogenides have drawn significant attention due to their unique structural phases and distinct properties in exploring magnetism and superconductivity. However, it remains a significant challenge to synthesize 2D Fe‐chalcogenides with specific phases in a controllable manner since Fe‐chalcogenides have multiple phases. Herein, a molecular sieve‐assisted strategy is reported for synthesizing ultrathin 2D iron sulfide on substrates via the chemical vapor deposition method. Using a molecular sieve and tuning growth temperatures to control the partial pressures of precursor concentrations, hexagonal FeS, tetragonal FeS, and non‐stoichiometric Fe₇S₈ nanoflakes can be precisely synthesized. The 2D h‐FeS, t‐FeS, and Fe₇S₈ have high conductivities of 5.4 × 10⁵ S m⁻¹, 5.8 × 10⁵ S m⁻¹, and 1.9 × 10⁶ S m⁻¹. 2D tetragonal FeS shows a superconducting transition at 4 K. The spin reorientation at ≈30 K on the non‐stoichiometric Fe₇S₈ nanoflakes with ferrimagnetism up to room temperature has also been observed. The controllable synthesis of various phases of 2D iron sulfide may provide a route for synthesizing other 2D compounds with various phases.