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Coupling Hydrogen Evolution to Clean and Sustainable Oxidations in Dye-Sensitised Photocatalysis

染料敏化光催化中析氢与清洁和可持续氧化的耦合

基本信息

批准号：
1800449
负责人：
金额：
--
依托单位：
University of Cambridge
依托单位国家：
英国
项目类别：
Studentship
财政年份：
2016
资助国家：
英国
起止时间：
2016 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=studentship-1800449
关键词：
Coupling Hydrogen Evolution Clean Sustainable

项目摘要

The holy grail of solar fuels is the ability to use solar energy to split water into its elements: hydrogen and oxygen. One of the newest approaches is dye sensitised photocatalysis which combines the fields of molecular catalysis and nanomaterials. In this approach, molecular dyes and catalysts are immobilised on a semiconductor nanoparticle such as titanium dioxide. When light is irradiated, the dye is excited and the photoelectrons are transferred to the conduction band of the semiconductor leading to efficient charge separation. They are later transferred to the molecular catalyst, where hydrogen evolution occurs. In a 'dream' system, water oxidation would allow for the regeneration of the dye. However, water oxidation is a kinetically slow process which is difficult to couple to hydrogen evolution. Furthermore, the production of oxygen is undesired as it damages the system, evolution of both hydrogen and oxygen in the same cell introduces a risk of explosion and oxygen itself has little market value. Until now, to study the hydrogen half reaction, sacrificial electron donors such triethanolamine are used as a substitute for water oxidation to allow for dye regeneration. However, sacrificial electron donors are expensive and their oxidation produces highly reactive radicals which decompose the catalyst. The aim of this PhD is to explore different alternatives to substitute the use of sacrificial reagents for an oxidation of an organic compound with faster kinetics and higher value than oxygen production. Different possible approaches might include direct one-electron radical substrate oxidation, oxidation by an organic radical or inorganic complex, or introduction of a redox mediator and coupling to another photocatalyst, forming a Z-scheme.

太阳能燃料的圣杯是能够利用太阳能将水分解成其元素：氢和氧。最新的方法之一是染料敏化光催化，它结合了分子催化和纳米材料领域。在这种方法中，分子染料和催化剂被固定在半导体纳米粒子（例如二氧化钛）上。当光照射时，染料被激发，光电子转移到半导体的导带，从而实现有效的电荷分离。随后它们被转移到分子催化剂，在那里发生氢气析出。在“梦想”系统中，水氧化将使染料再生。然而，水氧化是一个动力学缓慢的过程，很难与析氢耦合。此外，氧气的产生是不希望的，因为它会损坏系统，同一电池中氢气和氧气的释放会带来爆炸的风险，并且氧气本身几乎没有市场价值。到目前为止，为了研究氢半反应，三乙醇胺等牺牲电子供体被用作水氧化的替代品，以实现染料再生。然而，牺牲电子供体价格昂贵，并且它们的氧化会产生高反应性自由基，从而分解催化剂。该博士的目的是探索不同的替代方案来替代使用牺牲试剂来氧化有机化合物，其动力学更快，价值比氧气生产更高。不同的可能方法可能包括直接单电子自由基底物氧化、通过有机自由基或无机络合物的氧化、或引入氧化还原介体并与另一种光催化剂偶联，形成Z型。