Biomimetic MXene-Polyvinyl Alcohol Composite Hydrogel with Vertically Aligned Channels for Highly Efficient Solar Steam Generation

Solar steam generation, which utilizes sustainable solar energy to produce fresh water, is regarded as a facile and effective way to solve water scarcity issues. However, challenges remain in terms of inefficient water transfer and vapor release, low solar absorption and conversion efficiency, and hydrophobic photothermal materials. Herein, enlightened by water transport through internal microchannels in trees, a tree-inspired hydrogel (TIH) with vertically aligned channels incorporating MXene as the light absorber is fabricated. Due to the vertically aligned channels, the rapid transfer of water and unobstructed release of steam can be achieved. Furthermore, water state in molecular meshes can be changed by polymer-water interaction, and partial water can be activated to promote water evaporation. Excellent internal photothermal conversion efficiency and hydrophilicity of MXene are also conducive to evaporation. As a result, TIH has achieved an evaporation rate of 2.71 kg m(-2) h(-1) and energy efficiency of 90.7% under one sun irradiation, which is higher than membrane material and structure-disordered hydrogel. This design principle, expandable manufacturing route, and excellent performance provide a potential way and design concept for water purification and desalination.