Bio-inspired MXene coated wood-like ordered chitosan aerogels for efficient solar steam generating devices

Solar energy, as an endless clean energy, has great prospects for the use of water vapor from sewage purification and seawater desalination. Local heating of surface water has shown to maximize the energy efficiency of steam generation. Therefore, at first, the material is required to have a good ability of photo-thermal conversion. Among the photo-thermal converting materials, MXenes are arising candidates for effective photo-thermal conversion, which have shown excellent photo-thermal conversion efficiency and have been attempted for photo-thermal distillation. Although a high photo-thermal conversion efficiency has been realized, however, it is more challenging to prepare photo-thermal evaporating materials with rapid water transport capacity and generating solar steam. In this work, a photo-thermal distillation device was reported by combining a chitosan aerogel with a bio-inspired wood-like oriented porous structure prepared by directional freezing method, and Ti3C2Tx two-dimensional nanosheets coated with polyethyleneimine sprayed on the surface. The ordered microporous structure can quickly transport moisture from the bottom up to the evaporation surface by capillary force. The coating of Ti3C2Tx coated with polyethyleneimine on the evaporation surface has a strong ability to capture sunlight. The evaporation rate reaches 3.99 kg m−2 h−1 under the optical power density of 3000 W m−2 and the efficiency reaches 90%, indicating the broad application prospects as a photo-thermal conversion material for efficiently producing clean fresh water.