There is an increasing need to maintain the indoor humidity at a comfortable and healthy level without relying on high energy-consuming and potentially germ-infested air-conditioning systems. Water adsorbents exhibiting reversible moisture adsorption/desorption ability as well as sufficient antibacterial activity are highly expected to achieve humidity control in an autonomous and safe way. Metal−organic frameworks (MOFs) featuring high porosity and designability show potential in meeting these requirements in a singular platform. Given the low toxicity and the rich abundance of aluminum in nature, a family of isoreticular Al-terephthalate-based MOFs were systematically evaluated in terms of the static and kinetic water adsorption/ desorption and the photocatalytic bacteria-killing behavior. In particular, CAU-1-OH exhibits a desired working range (40−60% RH), a high working capacity (0.41 g g −1 ), an excellent cycle performance (500 cycles), and a high photocatalytic killing efficiency (99.94%) against Escherichia coli. As a proof of concept, the air filter prepared by coating CAU-1-OH on a commercial nonwoven fabric is capable of buffering against sudden humidity changes caused by the infiltration of outside air and effectively reducing the contamination of bioaerosol or particulate matter. The study significantly advanced the development of next-generation water adsorbents with antibacterial activity for residential humidity control.

Metal-organic frameworks (MOFs), featuring the ultrahigh surface area, high porosity, tunable geometrical and chemical properties, show potential applications in gas adsorption/separation, heterogenous catalysis, etc. As the ubiquity of water vapor in the ambient environment and industrial gas streams, it is necessary to study on interaction mechanism between MOFs and water molecules and develop highly water-stable MOFs with desirable water adsorption/desorption behaviors. It not only has the scientific significance, but also great importance in promoting the practical applications of MOFs. Given the tailorable abilities of pore size, pore volume, cavity hydrophilicity and water stability, MOFs provide unprecedented advantages to explore the well-defined porous sorbents in molecular level, which facilitates the realization of reversible water vapor uptake and release at expected relative pressure and temperature together with high working capacity. For now, a wide range of hydrolytically stable MOFs including high-valence metal (e.g. Cr 3＋ , Al 3＋ , Zr 4＋ , Ti 4＋ ) based frameworks have emerged as the advanced and promising porous sorbents for energy efficient applications, by utilizing water as eco-friendly adsorbate media and renewable heat. This review focuses on the following aspects: (1) the degradation mechanism of MOFs in liquid phase of water and the design concepts of hydrolytically stable MOFs by modulating their coordination bond based on the Pearson' hard/soft acid/base principle; (2) the physical or chemical water ad/desorption properties of MOFs; (3) the classification of numerous MOFs sorbents and conventional desiccants based on their hydrophilicity, which is approximately reflected by the relative humidity (RH) value of the inflection points (the RH where the steep uptake starts) in isotherms; (4) a variety of water adsorption-based applications of MOFs such as industrial gas dehydration, drinking water harvesting in the desert area, adsorption-based heat pump and indoor humidity regulation. Finally, the research priorities and development outlook are summarized and the future challenge with respect to water adsorption-based applications for the next-generation MOFs are outlined. Keywords metal-organic frameworks; water stability; water vapor adsorption; water vapor desorption; adsorption mechanism 1 引言 自 20 世纪 90 年代至今, 金属有机框架材料(metalorganic frameworks, 简称 MOFs)的快速发展和应用研究 令人瞩目. 作为一种多孔结晶材料, MOFs 材料具有丰 富的孔道结构、超高的比表面积(最高可达 7839 m 2 • g -1 )、低密度性(可低至 0.13 g•cm -3 )以及无机构筑单元 和有机配体设计组合的多样性 [1][2][3][4] . 这些特点使得 MOFs 材料在气体吸附与分离 [5][6][7][8][9][10] 、能源气体储存与转化 [11][12][13][14] 、 催化 [9,[15][16][17][18][19][20] 、环境污染物控制 [21][22][23][24][25][26][27] 、传感检测 [28] 等领域 展现出潜在的应用价值. 然而在上述吸附、分离与催化