Photocatalytic CO2 reutilisation to value-added products on metal-organic framework supported copper clusters

金属有机骨架支撑的铜簇上光催化二氧化碳再利用转化为增值产品

• 批准号: 2444571
• 金额: --
• 依托单位: University of Nottingham
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2444571
• 关键词: Photocatalytic; CO2; reutilisation; value; added

Atmospheric carbon dioxide (CO2) is one of the biggest contributors to climate change and as CO2 concentration in the atmosphere is constantly increasing, solutions to prevent CO2 emissions are urgently needed. Shifting to renewable, carbon neutral or negative technologies could prevent further growth of CO2 levels. However, these technologies are able to reduce only further CO2 emissions. Meanwhile, CO2 storage and conversion to value added- products are promising strategies to tackle the problem in the current situation. Nonetheless, conversion of CO2 to other chemicals instead of storing it would be needed to solve the issue. Promising approaches for CO2 reutilisation to value-added products is the reduction to methanol or the addition reaction to another molecule to produce useful chemicals, such as amino or carboxylic acids. CO2 can be converted to value-added products by photoactivation. Photoactivation saves energy and resources as it can be performed in the presence of catalysts and by using light instead of thermal energy and therefore, it would be more plausible option in terms of sustainability. Homogenous photocatalytic CO2 reutilisation has been performed in synthesis of numerous products using metal cluster complexes; however, performing it in a heterogenous manner would have advantages in terms of catalyst separation, durability, and reusability. Copper is frequently used for CO2 reutilisation due to its' ability to activate CO2 molecules. Single atom catalysts (SACs) or clusters of few atoms could increase the reactivity of the metal centre anchored in heterogeneous supports, while improving the atom-economy of the processes. To the best of our knowledge, CO2 reutilisation for the synthesis of amino acids or carboxylic acids using heterogeneous photocatalysts based on SACs has not been extensively explored. Proposed solution and methodology This project aims to design of heterogenous photocatalysis for CO2 reutilisation. The focus is on the use of metal-organic frameworks (MOFs) as photoactive supports for Cu as catalytic centres. MOFs are highly uniform and crystalline porous materials with an enormous surface area forming a framework structure between organic linkers and metal nodes. Consequently, MOFs offer a great platform for catalyst deposition and designing of tailored catalysts for various applications. Porphyrin and pyrene-based organic molecules have excellent light absorption properties in the visible light region and therefore they are applicable photosensitizers. These photosensitizers can be incorporated to MOF structures as the linkers allowing the photocatalytic processes to undergo in the heterogenous phase, facilitating catalysts recovery and extending their lifetime. Moreover, the photocatalytic properties of the MOFs could be further tuned by deposition of Cu on them by post-synthetic deposition techniques. Cu is proven to activate CO2 molecules as well as it can be incorporated with photosensitizers allowing tuning of photocatalytic properties. By applying Cu SACs or clusters on the MOFs, it could be possible to enhance efficiency of the MOF-based photocatalysts. The rigid and stable structure and wide mesopores of MOFs allow multiple strategies for post-synthetic catalyst deposition, such as atomic layer deposition (ALD), wet impregnation and magnetron sputtering as a solvent-free technique. To obtain deeper understanding of structure-activity relationship in the catalysts, catalytic reactions will be explored in situ by X-ray photoelectron spectroscopy and ex situ by spectroscopic and microscopic techniques. Finally, computational studies will be carried out for understanding of the experimental results comparing with theoretical models.

大气二氧化碳（CO2）是气候变化的最大贡献者之一，随着大气中CO2浓度的不断增加，迫切需要防止CO2排放的解决方案。转向可再生、碳中和或负技术可以防止二氧化碳水平的进一步增长。然而，这些技术只能进一步减少二氧化碳排放。同时，CO2封存和转化为增值产品是当前形势下解决这一问题的有前途的战略。然而，要解决这一问题，需要将二氧化碳转化为其他化学品，而不是储存起来。将二氧化碳再利用为增值产品的有前途的方法是还原为甲醇或与另一种分子加成反应以产生有用的化学品，如氨基或羧酸。CO2可以通过光活化转化为增值产品。光活化可以节省能源和资源，因为它可以在催化剂的存在下进行，并且使用光而不是热能，因此，就可持续性而言，它将是更合理的选择。均相光催化CO2再利用已经在使用金属簇合物合成许多产品中进行;然而，以非均相方式进行将在催化剂分离、耐久性和可重复使用性方面具有优势。铜由于其活化CO2分子的能力而经常用于CO2再利用。单原子催化剂（SAC）或原子数较少的簇可以提高固定在多相载体上的金属中心的反应活性，同时提高过程的原子经济性。据我们所知，使用基于SAC的非均相光催化剂合成氨基酸或羧酸的CO2再利用尚未被广泛探索。建议的解决方案和方法本项目旨在设计用于CO2再利用的非均质碳源。重点是使用金属有机框架（MOFs）作为光活性支持Cu作为催化中心。MOF是高度均匀的结晶多孔材料，具有巨大的表面积，在有机连接剂和金属节点之间形成框架结构。因此，MOFs为催化剂沉积和设计用于各种应用的定制催化剂提供了一个很好的平台。卟啉类和芘类有机分子在可见光区具有优良的光吸收性能，是一类很有应用前景的光敏剂。这些光敏剂可以作为连接剂掺入到MOF结构中，允许光催化过程在非均相中进行，促进催化剂回收并延长其寿命。此外，MOFs的光催化性能可以通过合成后沉积技术在其上沉积Cu来进一步调节。Cu被证明可以激活CO2分子，并且它可以与光敏剂结合，从而可以调节光催化性能。通过在MOF上施加Cu SAC或簇，可以提高基于MOF的光催化剂的效率。MOFs的刚性和稳定的结构以及宽的介孔允许用于合成后催化剂沉积的多种策略，例如原子层沉积（ALD）、湿浸渍和磁控溅射作为无溶剂技术。为了更深入地了解催化剂的结构-活性关系，将通过X射线光电子能谱和光谱和显微镜技术对催化反应进行原位探索。最后，将进行计算研究，以了解实验结果与理论模型的比较。