Light-powered bioelectrochemical conversion of CO2 for the synthesis of value-added chemicals based on gas-diffusion electrodes and enzyme cascades

近年来，二氧化碳的(生物)电化学转化为附加值化学品受到了极大的关注。相关的经济上可行和可持续的系统将减少全球二氧化碳排放量，并避免使用化石燃料进行碳基化学品生产所带来的弊端。在这个项目中，我们将开发新的氧化还原聚合物，它允许氧化还原蛋白甲酸脱氢酶(FDH)的扭曲，该酶使用气体扩散电极可逆地催化二氧化碳到甲酸盐的相互转化。然后，这一活性二氧化碳还原层将被耦合到酶的级联中，在酶的级联中，C1前体甲酸盐进一步转化为增值化学物质甲醇。整个酶级联将固定在电极表面，以确保该方法对技术相关系统的适用性。开发出的二氧化碳减排生物电极随后将与光电化学电池中的高电流密度聚合物/光系统II生物阳极耦合，该电池允许将二氧化碳作为唯一的碳原料通过太阳能驱动生产甲醇。所提议的系统的优点是显而易见的：(I)使用3D结构的氧化还原聚合物，通过同时为生物催化剂提供合适的亲水环境，将使大量生物催化剂能够连接到电极表面；(Ii)气体扩散电极的实施将克服质量传输的限制，以及(Iii)利用光来为甲醇的生产提供动力，将导致可持续和环保的整个制造过程。

The (bio)electrochemical conversion of CO2 to value added chemicals has gained great attention during recent years. Related economically viable and sustainable systems would decrease the global CO2 volume and circumvent drawbacks that are coupled to the use of fossil fuels for carbon base chemical production. In this project we will develop new redox polymers that allow for the wring of the redox protein formate dehydrogenase (FDH) that catalyses reversibly the interconversion of CO2 to formate using gas diffusion electrodes. This active CO2 reduction layer will then be coupled to enzyme cascades in which the C1 precursor formate is further converted into the value-added chemical methanol. The entire enzyme cascade will be immobilized at the electrode surface to ensure applicability of the approach towards technical relevant systems. The developed CO2 reducing biocathode will then be coupled to a high current density polymer/photo-system II-based bioanode in a photoelectrochemical cell that allows for solar-driven production of methanol from CO2 acting as the only carbon feedstock. The advantages of the proposed system are obvious: (i) the use of a 3D-structured redox polymer will enable the wiring of a high number of biocatalyst to the electrode surface by simultaneously providing a suitable hydrophilic environment for the biocatalyst; (ii) the implementation of gas diffusion electrodes will overcome mass transport limitations and (iii) the use of light to power the production of methanol will lead to a sustainable and eco-friendly overall manufacturing process.