Directional Thermal Rectification via Global Symmetry Breaking in Semimetal W ₂ S ₃ Towards Extraordinary Solar Steam Generation

ABSTRACT Solar‐driven interfacial evaporation holds significant promise for mitigating global freshwater scarcity, yet its practical implementation is fundamentally limited by the suboptimal solar‐to‐thermal conversion efficiency of conventional materials, which suffer from narrow spectral absorption and uncontrolled thermal dissipation. Herein, for the first time, we propose an atomic‐level symmetry‐breaking design principle to address these challenges, as exemplified by tungsten trisulfide (W 2 S 3 ) with precisely engineered symmetry‐broken lattices. The symmetry‐broken W 2 S 3 architecture enables exceptional photothermal conversion and thermal localization by tailoring band‐edge states to simultaneously enhance broadband light absorption and accelerate hot‐carrier relaxation and recombination, while directional thermal rectification effectively regulates heat transport pathways to minimize parasitic energy losses. By incorporating W 2 S 3 into a 3D porous hydrogel evaporator, an extremely high evaporation rate of 7.862 kg m −2 h −1 is achieved, along with a competitive solar steam efficiency of 92.2%, approaching the theoretical thermodynamic efficiency limit of 92.5% under 1 sun illumination. This work establishes a transformative framework for designing advanced photothermal materials and propelling the development of next‐generation solar‐driven desalination technologies.