Bio-inspired (Fe,Ni)S nano-catalysts for CO2 conversion

尽管二氧化碳具有很高的热力学稳定性，但生物系统能够激活分子并将其转化为一系列有机分子，所有这些都是在适度的条件下进行的。显然，如果我们能够模仿大自然，在不需要极端反应条件的情况下，成功地将二氧化碳转化为有用的化学中间体，好处将是巨大的：导致气候变化的主要气体之一将成为化工和制药行业的重要原料！在太古代洋底温暖的碱性泉水中形成的铁镍硫化物薄膜越来越被认为是导致生命出现的一系列化学反应的早期催化剂。醋酸盐、甲醛、氨基酸和核酸碱基--生命的有机前体分子--的厌氧生产被认为是由小立方烷(Fe，Ni)S簇合物(例如Fe5NiS8)催化的，这些簇合物在结构上与当今硫化物矿物如闪锌矿(Fe3S4)和麦基纳维石(FeS)的表面相似。现代证实硫化物簇合物作为催化剂的重要性是由许多现代厌氧生命形式所必需的蛋白质提供的，如铁氧还蛋白、氢酶、一氧化碳脱氢酶或乙酰辅酶A合成酶(ACs)，所有这些蛋白质都保留了铜矿(Fe，Fe3S4)和乙酰辅酶A合成酶Ni)S具有云母般的局部结构，既可以作为电子转移中心，也可以作为代谢挥发物如H2、CO和CO2的活性中心。鉴于(Fe，Ni)S矿物作为生物前二氧化碳转化催化剂的重要性，我们建议采用先进的计算和实验相结合的方法来设计、合成、测试、表征、评估和生产用于二氧化碳活化和化学修饰的规模化新型铁镍硫化物纳米催化剂。(Ni，Fe)S纳米粒子的设计灵感来自于现代生物系统中的活性中心，这些活性中心是为二氧化碳转化为生物物质的复杂氧化还原过程量身定做的。该项目的科学成果将是设计和开发一种新型硫化物催化剂，专门用于二氧化碳还原和转化为化学原料分子，随后将制造一种自动化中试装置。具体成果包括：i.从原子水平了解(Fe，Ni)S纳米催化剂的尺寸、表面结构和组成对稳定性、氧化还原性能和催化活性的影响；ii.开发具有定制催化性能的Fe-M-S纳米团簇和粒子的新合成方法(M=Ni和其他有希望的过渡金属掺杂)；二氧化碳活化/转化用纳米铅催化剂的快速制备及电催化筛选；开发和应用一种新的一体化设计--合成--筛选方法，为所需的反应生产有效的纳米催化剂；v.建造一个原型装置，能够在典型的低电压下催化二氧化碳的低温反应生成产品，这种反应可以从太阳能获得；从经济、环境和社会影响评估确定在第二阶段扩大规模的最佳工艺第一阶段终点的目标是制造一种能够收集太阳能的光电化学反应器，以(I)从碳捕获工艺流中回收二氧化碳，(Ii)将其与氢结合，以及(Iii)催化反应生成产物。在项目的第二阶段，原型将被开发成一个扩大的商业可行的装置，使用最佳催化剂(S)，从(I)反应性/对所需反应的选择性；(Ii)经济影响；以及(Iii)环境、伦理和社会考虑。

Despite the high thermodynamic stability of CO2, biological systems are capable of both activating the molecule and converting it into a range of organic molecules, all of which under moderate conditions. It is clear that, if we were able to emulate Nature and successfully convert CO2 into useful chemical intermediates without the need for extreme reaction conditions, the benefits would be enormous: One of the major gases responsible for climate change would become an important feedstock for the chemical and pharmaceutical industries! Iron-nickel sulfide membranes formed in the warm, alkaline springs on the Archaean ocean floor are increasingly considered to be the early catalysts for a series of chemical reactions leading to the emergence of life. The anaerobic production of acetate, formaldehyde, amino acids and the nucleic acid bases - the organic precursor molecules of life - are thought to have been catalyzed by small cubane (Fe,Ni)S clusters (for example Fe5NiS8), which are structurally similar to the surfaces of present day sulfide minerals such as greigite (Fe3S4) and mackinawite (FeS).Contemporary confirmation of the importance of sulfide clusters as catalysts is provided by a number of proteins essential to modern anaerobic life forms, such as ferredoxins, hydrogenases, carbon monoxide dehydrogenase (CODH) or acetyl-coenzyme A synthetase (ACS), all of which retain cubane (Fe,Ni)S clusters with a greigite-like local structure, either as electron transfer sites or as active sites to metabolise volatiles such as H2, CO and CO2. In view of the importance of (Fe,Ni)S minerals as catalysts for pre-biotic CO2 conversion, we propose employing a robust combination of state-of-the-art computation and experiment in a grand challenge to design, synthesise, test, characterise, evaluate and produce for scale-up novel iron-nickel sulfide nano-catalysts for the activation and chemical modification of CO2. The design of the (Ni,Fe)S nano-particles is inspired by the active sites in modern biological systems, which are tailored to the complex redox processes in the conversion of CO2 to biomass.The scientific outcome of the Project will be the design and development of a new class of sulphide catalysts, tailored specifically to the reduction and conversion of CO2 into chemical feedstock molecules, followed by the fabrication of an automated pilot device. Specific deliverables include:i. Atomic-level understanding of the effect of size, surface structure and composition on stabilities, the redox properties and catalytic activities of (Fe,Ni)S nano-catalysts;ii. Development of novel synthesis methods of Fe-M-S nano-clusters and -particles with tailored catalytic properties (M = Ni and other promising transition metal dopants);iii. Rapid production and electro-catalytic screening of lead nano-catalysts for the activation/conversion of CO2;iv. Development and application of a new integrated design-synthesis-screening approach to produce effective nano-catalysts for desired reactions;v. Construction of a prototype device capable of catalysing low-temperature reactions of CO2 into products at typical low-voltages, that can be obtained from solar energy; vi. Identification of optimum process for scale-up in Stage 2, from the Economic, Environmental and Societal Impact evaluationThe target at the end-point of Stage 1 is the fabrication of a photo-electrochemical reactor capable of harvesting solar energy to (i) recover CO2 from carbon capture process streams, (ii) combine it with hydrogen, and (iii) catalyse the reaction into product. In Stage 2 of the project, the prototype will be developed into a scaled-up commercially viable device, using optimum catalyst(s) in terms of (i) reactivity/selectivity towards the desired reaction; (ii) economic impact; and (iii) environmental, ethical and societal considerations.