Directional Thermal Rectification via Global Symmetry Breaking in Semimetal W2S3 Towards Extraordinary Solar Steam Generation

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.