Wang Feng, Wang Baoliang, Wang Yuankun, Wu Defeng
School of Chemistry & Chemical Engineering, Yangzhou University, Yangzhou, Jiangsu Province 225002, PR China.
School of Chemistry & Chemical Engineering, Yangzhou University, Yangzhou, Jiangsu Province 225002, PR China; Provincial Key Laboratories of Green & Functional Materials and Environmental Chemistry, Yangzhou, Jiangsu Province 225002, PR China.
J Colloid Interface Sci. 2025 Nov 15;698:138104. doi: 10.1016/j.jcis.2025.138104. Epub 2025 Jun 6.
Covalent organic frameworks (COFs) bulk materials have attracted much interest recently in the seawater desalination field. To improve water supply and photothermal conversion efficiency is vital for designing COF-based evaporators. In this study, a bilayer COF-based aerogel with multilevel architectures and tailorable solar-driven desalination performance was developed. Four types of diamines with various groups (-H, -CH, -OH, -OCH) were used to construct COF part and it was found that the presence of oxygen-containing groups improved hydrophilicity of the aerogel and reduced water evaporation enthalpy, which guaranteed sufficient water transport with the help of the aligned pores formed via the directional freezing treatment. The mixed metal organic frameworks (MOF)/MXene particles were used as surface coating for the COF part and the photothermal conversion efficiency could be optimized by regulating the mole ratio of MOF/MXene. The enhanced surface roughness improved the broadband solar absorption (95.3 %, 250-2500 nm) of the coating and the formed channels in the coating favored reducing surface salt deposition. Thus, the as-developed COF aerogel evaporator had desirable desalination performance. Owing to the strongest hydrophilicity and the lowest evaporation enthalpy, the hydroxylated diamine-constructed aerogel coated with MOF/MXene (molar ratio 1/2) exhibited the best evaporation rate (2.67 kg mh) and solar-to-vapor efficiency (94 %) among all the aerogels, and the desalination performance was stable in harsh environment. Moreover, the aerogel possessed multimodal working ability, adsorbing pollutants while desalinating seawater. This work provided an attractive way to structurally architect COF-based functional materials.
共价有机框架（COF）块状材料最近在海水淡化领域引起了广泛关注。提高供水和光热转换效率对于设计基于COF的蒸发器至关重要。在本研究中，开发了一种具有多级结构和可定制太阳能驱动脱盐性能的双层COF基气凝胶。使用四种带有不同基团（-H、-CH、-OH、-OCH）的二胺来构建COF部分，发现含氧基的存在提高了气凝胶的亲水性并降低了水蒸发焓，这借助于定向冷冻处理形成的排列孔隙保证了充足的水传输。混合金属有机框架（MOF）/MXene颗粒用作COF部分的表面涂层，通过调节MOF/MXene的摩尔比可以优化光热转换效率。增强的表面粗糙度提高了涂层的宽带太阳能吸收率（95.3%，250 - 2500 nm），并且涂层中形成的通道有利于减少表面盐沉积。因此，所开发的COF气凝胶蒸发器具有理想的脱盐性能。由于亲水性最强且蒸发焓最低，涂覆有MOF/MXene（摩尔比1/2）的羟基化二胺构建的气凝胶在所有气凝胶中表现出最佳的蒸发速率（2.67 kg m⁻¹ h⁻¹）和太阳能到蒸汽效率（94%），并且在恶劣环境下脱盐性能稳定。此外，该气凝胶具有多模式工作能力，在淡化海水的同时吸附污染物。这项工作为基于COF的功能材料的结构设计提供了一种有吸引力的方法。
