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

近年来，二氧化碳生物电化学转化为高附加值化学品的研究受到了广泛关注。相关的经济上可行和可持续的系统将减少全球二氧化碳量，并避免与使用化石燃料进行碳基化学生产有关的缺点。在这个项目中，我们将开发新的氧化还原聚合物，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相互转化为甲酸。该活性CO2还原层随后与酶级联连接，其中C1前体甲酸酯进一步转化为增值化学甲醇。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。开发的二氧化碳还原生物阴极将在光电化学电池中与高电流密度聚合物/基于光系统ii的生物阳极耦合，从而允许太阳能驱动的甲醇生产，二氧化碳作为唯一的碳原料。所提出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将通过同时为生物催化剂提供合适的亲水性环境，使大量生物催化剂连接到电极表面；（ii）气体扩散电极的实施将克服质量传输的限制；（iii）利用光为甲醇的生产提供动力将导致一个可持续和环保的整体制造过程。

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.