Photocatalytic covalent organic frameworks for hydrogen production and storage

COFs是最有前途的储氢材料之一，它们重量轻，坚固耐用，易于合成，具有高储氢容量（bbb70wt .%），并且长期使用比金属有机框架（MOFs）稳定得多。然而，与mof一样，这些材料是网状聚合物，通常具有均匀的孔径。虽然这使得气体分子很容易进入，但几乎没有什么能阻止它们轻易离开，事实上，在环境温度下，COFs和mof的储氢能力通常是在低温下测量时的三分之一左右。近年来，光催化聚合物和框架也作为令人兴奋的新候选物出现在从水到氢的演化中，有机分子本质上无限的多功能性和模块化性质使我们能够微调光学和电子特性，从而提高催化性能。该项目将生产基于二苯并噻吩- s， s -二氧化氮的光催化分子结构，这是一种最有希望从水中制氢的有机片段之一，它将通过非共价相互作用锚定在COF表面的孔隙上，为氢从水中析出创造位点，并减小孔隙的大小，使它们容易渗透到氢，但不能渗透到氧，以确保COF只富含氢。在第一个实例中，目标是在298K时实现5 wt.%的重力容量。美国能源部已经为轻型汽车的车载氢存储设定了到2020年重量容量为4.5 wt %，到2025年重量容量为5.5 wt %的目标，本文提出的方法是实现这一目标的真正途径。这种方法将提高富氢COFs在环境温度下的热稳定性，并最终允许控制氢气的产生、储存和释放。

COFs are among the most promising hydrogen storage materials, they are lightweight, robust and easily synthesised with high hydrogen storage capacity (>7 wt.%) and are much more stable than metal organic frameworks (MOFs) for long term use. However, like MOFs, these materials are network polymers, often with uniform pore sizes. While this allows gas molecules to enter easily there is little to stop them leaving just as readily, indeed at ambient temperatures the hydrogen storage capacity of both COFs and MOFs is typically around a third of that when measured at cryogenic temperatures.In recent years, photocatalytic polymers and frameworks have also emerged as exciting new candidate in hydrogen evolution from water, the essentially infinite versatility and modular nature of organic molecules allows us to fine tune optical and electronic properties and thereby catalytic performance. This project will produce photocatalytic molecular tectons based on dibenzothiophene-S,S-dioxide - one of the most promising organic fragments in hydrogen production from water - which will anchor over the pores in the surface of the COF through non-covalent interactions to create sites for hydrogen evolution from water and to reduce the size of the pores making them readily permeable to hydrogen but not oxygen to ensure that the COF becomes enriched in hydrogen exclusively, targeting a gravimetric capacity of 5 wt.% at 298K in the first instance. The US DOE has set a target gravimetric capacity of 4.5 wt % by 2020 and 5.5 wt % by 2025 for onboard hydrogen storage for light vehicles and the approach proposed here presents a genuine route to attaining this goal. This approach will increase the thermal stability of the hydrogen enriched COFs at ambient temperatures and ultimately permit controlled generation, storage and release of hydrogen.