Free-Standing and Highly Tough 3D Network of Carbon Nanotubes and MXene Constructed by Facile "Egg-Box" Coordination Mechanism for High-Efficiency Solar Evaporator

Solar steam generation to generate steam through solar light-driven surface evaporation can be an attractive methodology that utilizes green and inexhaustible solar energy to generate water steam and fresh water with superior efficiency. However, some drawbacks of the current photothermal conversion materials such as complicated fabrication process, high cost, and low salt tolerance often heavily restrict their wide applications. Herein, a green and low-cost method is designed and developed for constructing a free-standing, elastic, and highly tough 3D network of carbon nanotubes (CNTs) and MXene through an efficient "egg-box" coordination mechanism in only one step for high-efficiency water evaporation. When the mass ratios of MXene and CNTs are designed at 1:1.5 and cross-linked with sodium alginate and CaCl2, the obtained MCS-3 shows the most excellent light absorption and hydrophilicity, leading to the best evaporation rate of 1.644 kg m-2 h-1, and the highest photothermal conversion efficiency of 96%. Moreover, subject to different harsh environments and durability tests, MCS-3 also shows desired structural stability and evaporation performance. As demonstrated by its extraordinary photothermal evaporation properties, MCS-3 can envision a wide range of commercial applications covering wastewater purification, brine seawater, desalination, etc. The mechanically strong MXene/carbon nanotubes/sodium alginate composites are prepared by a facile one-step "egg-box" coordination mechanism and displays superior water evaporation rate, high photothermal conversion efficiency, excellent desalination ability, self-desalination capability, long-time running stability, and promising practical application prospect.image (c) 2023 WILEY-VCH GmbH