Photocatalytic covalent organic frameworks for hydrogen production and storage

COF是最有前景的储氢材料之一，它们重量轻、坚固、易于合成、储氢容量高(&gt；7wt.%)，而且比金属有机骨架(MOF)更稳定，可长期使用。然而，像MOF一样，这些材料是网络聚合物，通常具有统一的孔大小。虽然这使得气体分子可以很容易地进入，但几乎没有什么可以阻止它们同样容易离开，事实上，在常温下，COF和MOF的储氢容量通常是在低温下测得的三分之一左右。近年来，光催化聚合物和骨架也成为从水中析氢的令人兴奋的新候选者，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性质，从而催化性能。该项目将生产基于二苯并噻吩基的光催化分子Tecton-S、S-二氧化物-水制氢中最有希望的有机片段之一-将通过非共价相互作用锚定在COF表面的孔上，为水中析氢创造场所，并缩小孔的大小，使其容易渗透到氢而不是氧，以确保COF只富含氢，最初的目标是298K时5wt.%的重量能力。美国能源部为轻型汽车车载储氢设定了到2020年4.5wt%和2025年5.5wt%的目标，这里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COF在常温下的热稳定性，并最终允许受控地产生、存储和释放氢。

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.