Department of Biology, Washington University in Saint Louis, St. Louis, MO, 63130, United States of America.
Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, MO, United States of America.
Nanotechnology. 2021 Jan 15;32(3):035103. doi: 10.1088/1361-6528/abbe58.
Microbial electrosynthesis (MES) is an emerging technology that can convert carbon dioxide (CO) into value-added organic carbon compounds using electrons supplied from a cathode. However, MES is affected by low product formation due to limited extracellular electron uptake by microbes. Herein, a novel cathode was developed from chemically synthesized magnetite nanoparticles and reduced graphene oxide nanocomposite (rGO-MNPs). This nanocomposite was electrochemically deposited on carbon felt (CF/rGO-MNPs), and the modified material was used as a cathode for MES production. The bioplastic, polyhydroxybutyrate (PHB) produced by Rhodopseudomonas palustris TIE-1 (TIE-1), was measured from reactors with modified and unmodified cathodes. Results demonstrate that the magnetite nanoparticle anchored graphene cathode (CF/rGO-MNPs) exhibited higher PHB production (91.31 ± 0.9 mg l). This is ∼4.2 times higher than unmodified carbon felt (CF), and 20 times higher than previously reported using graphite. This modified cathode enhanced electron uptake to -11.7 ± 0.1 μA cm, ∼5 times higher than CF cathode (-2.3 ± 0.08 μA cm). The faradaic efficiency of the modified cathode was ∼2 times higher than the unmodified cathode. Electrochemical analysis and scanning electron microscopy suggest that rGO-MNPs facilitated electron uptake and improved PHB production by TIE-1. Overall, the nanocomposite (rGO-MNPs) cathode modification enhances MES efficiency.
微生物电合成（MES）是一种新兴技术，它可以利用阴极提供的电子将二氧化碳（CO）转化为有价值的有机碳化合物。然而，由于微生物对细胞外电子的摄取有限，MES 的产物形成受到限制。在此，开发了一种由化学合成的磁铁矿纳米粒子和还原氧化石墨烯纳米复合材料（rGO-MNPs）组成的新型阴极。该纳米复合材料通过电化学沉积在碳纤维毡（CF/rGO-MNPs）上，并将改性材料用作 MES 生产的阴极。通过 Rhodopseudomonas palustris TIE-1（TIE-1）生产的生物塑料聚羟基丁酸酯（PHB），从装有改性和未改性阴极的反应器中进行测量。结果表明，磁铁矿纳米颗粒锚定石墨烯阴极（CF/rGO-MNPs）表现出更高的 PHB 产量（91.31±0.9 mg l）。这比未改性的碳纤维毡（CF）高约 4.2 倍，比以前使用石墨报告的高 20 倍。这种改性阴极增强了电子摄取到-11.7±0.1 μA cm，比 CF 阴极高约 5 倍（-2.3±0.08 μA cm）。改性阴极的法拉第效率比未改性阴极高约 2 倍。电化学分析和扫描电子显微镜表明，rGO-MNPs 促进了电子摄取并提高了 TIE-1 的 PHB 产量。总体而言，纳米复合材料（rGO-MNPs）阴极修饰提高了 MES 的效率。
