Bioinspired design of integral molded Janus silk fibroin-MXene evaporator for efficient solar vapor generation

Solar vapor generation is a promising sustainable technology that uses solar distillation to produce fresh water from seawater and wastewater, helping relieve global water resource shortage. Here, inspired by naturally grown integrally molded mulberry leaves with a Janus hydrophilic and hydrophobic structure, a novel, simple, and efficient integrated molding method is proposed to break through the limitations of the traditional split manufacturing strategy and realizes the integrated formation of Janus evaporator. Based on the spontaneous sedimentation characteristics of MXene in silk fibroin solution and its regulation of mesoscopic structure and hydrophilicity of silk fibroin, layered structures with different compositions and hydrophilicities were obtained in one step. Meanwhile, ethanol and glutaraldehyde were added to construct a physical crystallization-chemical crosslinking dual stabilization structure in silk fibroin. Our evaporator has the evaporation rate of 3.07 kg·m⁻²·h⁻¹ and the efficiency of 86.8% under 1 sun and maintains high evaporation performance under various extreme test conditions including vigorous washing, repeated compression, and high-intensity ultraviolet (UV) irradiation. Additionally, the evaporator performs well in practical application scenarios, its evaporation rate in the simulated Dead Sea seawater exceeds 2.13 kg·m⁻²·h⁻¹, and more than 99.9% of the salt, heavy metal ions, oil pollution, and dyes are purified.