Solar fuels from sustainable feedstock using Earth-abundant catalysts: Can light drive affordable electrocatalysts for fuel production?

拟议的研究目标是从可持续原料和可再生能源合成燃料的新技术。这是一项重要的工作，因为全球五分之三的能源使用是以燃料燃烧的形式用于运输和供暖。虽然太阳能和风能等可再生能源发电有望减少发电的碳排放，但只有五分之二的最终用途能源是电力。寻找可持续和具有成本效益的方法来实现运输和供暖的脱碳，这在全球范围内至关重要。利用唯一的无限可再生能源--太阳能--从二氧化碳原料合成燃料将是一个理想的解决方案。然而还没有可行的技术被开发出来，为什么呢？传统的二氧化碳转化催化剂是基于贵金属的，价格昂贵，不适合大规模部署。铼是最广泛使用的二氧化碳还原催化剂的基础，非常昂贵和稀有。它的类似物锰的丰度要高出130万倍，占地壳的0.1%。2011年，研究人员发现，具有二亚胺配体和羰基的Mn配合物在减少CO2方面可能比其Re类似物更活跃。这些催化剂现在用于电化学还原，其中电子从“干线”流向电极，然后流向催化剂，最后流向CO2。2016年，我们开发了一种新型的多功能锰基催化剂，可以附着在表面上。我们能否使用可再生能源来激活这些廉价、多功能、地球资源丰富的催化剂？到目前为止，主要的障碍是这些催化剂是光敏的，我们不能直接使用阳光来激活它们。我们建议将廉价的催化剂（Mn基）与可用的原料（CO2）和可再生能源（太阳能）结合在一个间接使用阳光的装置中。我们将在吸光半导体领域最近（2016年）取得的进展的基础上，研究一种可以提供所寻求的突破的集成技术。整体愿景是一种基于板的技术（很像太阳能光伏板），可以大量廉价制造，吸收阳光并将太阳能转移到固定在光吸收表面上的催化剂。该催化剂在水基电解质中加入CO2，来自太阳光的能量将CO2还原为CO，这是一种反应性中间体，进一步的众所周知的反应可以制造燃料。我们的计划是使用一种特殊的光吸收电极（由TiO 2保护的Cu 2 O/AlZnO），该电极已被证明与稀缺的Al 2 O3基催化剂组合非常有效。我们将用铼来代替高丰度的锰催化剂，并测量它们的有效性。催化剂需要固定在电极上，不能直接暴露在阳光下。我们的研究将克服这些限制，通过化学改性的催化剂将其附着到光吸收半导体电极，并通过从结构的背面照射吸收电极，此外，我们将建立一个原型的工业过程方案，我们将调查拟议设备的能源经济性能和碳排放。这将使我们能够评估该技术在缓解气候变化和提供具有成本效益的燃料方面可能产生的影响。我们拥有一支研究人员团队，其专业知识涵盖化学、物理、材料和设备以及技术经济分析--这对此类研究的成功至关重要。总的来说，找到一种方法来为这些廉价，多功能的催化剂提供太阳能，将朝着为所有人生产燃料和能源的清洁，可再生方式迈出一大步。它将推动对更便宜的催化剂、材料和设备的研究，提高生活质量，并帮助地球。

The proposed research targets new technology to synthesise fuels from sustainable feedstocks and renewable energy. This is important work since three fifths of all global energy usage is in the form of fuel burning for transportation and heating. While renewable electricity generation from solar and wind amongst others is on track to reduce the carbon emissions of electricity generation, only two fifths of end use energy is in the form of electricity. It is globally critical to find sustainable and cost effective ways to decarbonise transport and heating. Synthesising fuels from CO2 feedstocks using the only infinite source of renewable energy - solar - would be an ideal solution. Yet no viable technology have been developed.Why not?Traditional catalysts for conversion of CO2 are Nobel-metal based, expensive, and not suitable for mass deployment. Rhenium, which is the basis of the most broadly used catalysts for CO2 reduction, is extremely expensive and rare. Its analog, Manganese, is 1.3 million times more abundant, constituting 0.1% of the Earth's crust. In 2011, researchers showed that Mn-complexes with diimine ligands and carbonyls could be even more active then their Re analogs in reducing CO2. These catalysts are used now used in electrochemical reduction, where the electrons flow from the "mains" to the electrode, then to the catalyst, and finally to CO2. In 2016, we developed a new class of versatile Mn-based catalysts which can be attached to surfaces.Can we use renewable energy to activate these cheap, versatile, Earth-abundant catalysts?The major obstacle so far has been that these catalysts are light-sensitive, and we can not use sunlight to activate them directly. We propose to combine the cheap catalysts (Mn-based) with available feedstock (CO2) and renewable energy (solar) in a device which uses sunlight indirectly. We will build on recent (2016) progress in light-absorbing semiconductors and investigate an integrated technology that could provide the sought after breakthrough. The overall vision is a plate based technology (much like a solar photovoltaic panel) that can be manufactured cheaply in high volumes, that absorbs sunlight and transfers the solar energy to a catalyst that is anchored on the light absorbing surface. The catalyst is fed CO2 in a water based electrolyte and the energy from the sunlight reduces the CO2 to CO, a reactive intermediate from which further, well-known, reactions can make fuels.Our plan is to use a particular light absorbing electrode (Cu2O/AlZnO protected by TiO2) that has been shown to be highly effective in combination with scarce rhenium based catalysts. We will substitute Rhenium for highly abundant Manganese catalysts and measure how effective they are. The catalyst needs to be anchored to the electrode and must not be directly exposed to sunlight. Our research will overcome these constraints using chemical modification of the catalyst to attach it to the light-absorbing semiconductor electrode, and by illuminating the absorbing electrode from the back of the structure.In addition, we will build a prototype industrial process scheme from which we will investigate the energy economic performance and carbon emissions of the proposed device. This will allow us to evaluate the likely impact of the technology in terms of mitigation of climate change, and in providing cost effective access to fuels.We have a team of researchers with expertise spanning chemistry, physics, materials and devices, and techno-economic analysis - the cross-section that is vital for such research to succeed. Overall, finding a way to solar-power these cheap, versatile catalysts, will make a huge step forward towards clean, renewable ways of producing fuels, and energy, for all. It will invigorate research in cheaper catalysts, materials and devices, improve quality of life - and help the Planet.