标题： 理解与控制MOF-74的水稳定性 显示英文标题

标题： Understanding and Controlling Water Stability of MOF-74

摘要： 金属有机框架（MOF）材料，尤其是MOF-74，在许多技术重要的过程中具有良好的性能。 然而，它们在潮湿条件下的不稳定性严重限制了实际应用。 我们表明，这种不稳定性以及在潮湿条件下MOF-74的CO$_2$吸附能力的降低源于金属中心的水解离反应H$_2$O$\rightarrow$OH+H。 在该解离之后，OH基团与金属中心配位，解释了MOF的CO$_2$吸附能力的降低。 因此，这种降低强烈依赖于MOF-74对水解离反应的催化活性。 我们进一步表明——虽然水分子本身对MOF-74的晶体结构只有微不足道的影响——解离反应的OH和H产物显著削弱了MOF框架，并导致观察到的晶体结构破坏。 有了这一知识，我们提出了一种通过修改MOF-74结构以增加水解离能垒的方法，从而控制潮湿条件下的系统稳定性。 显示英文摘要

摘要： Metal organic framework (MOF) materials in general, and MOF-74 in particular, have promising properties for many technologically important processes. However, their instability under humid conditions severely restricts practical use. We show that this instability and the accompanying reduction of the CO$_2$ uptake capacity of MOF-74 under humid conditions originate in the water dissociation reaction H$_2$O$\rightarrow$OH+H at the metal centers. After this dissociation, the OH groups coordinate to the metal centers, explaining the reduction in the MOF's CO$_2$ uptake capacity. This reduction thus strongly depends on the catalytic activity of MOF-74 towards the water dissociation reaction. We further show that-while the water molecules themselves only have a negligible effect on the crystal structure of MOF-74-the OH and H products of the dissociation reaction significantly weaken the MOF framework and lead to the observed crystal structure breakdown. With this knowledge, we propose a way to suppress this particular reaction by modifying the MOF-74 structure to increase the water dissociation energy barrier and thus control the stability of the system under humid conditions.