Microbial electrosynthesis is a promising technology that recovers energy from wastewater while converting CO2 into CH4. Constructing a biocathode with both strong H2-mediated and direct electron transfer capacities is crucial for efficient startup and long-term stable CH4 production. This study found that introducing carboxyl groups onto the cathode effectively enhanced both electron transfer pathways, improving the reduction rate and coulombic efficiency of CH4 production and increasing the CH4 yield by 2–3 times. Carboxyl groups decreased the overpotential for H2 evolution and increased current density, thereby enhancing H2-mediated electron transfer. Additionally, carboxyl groups increased the relative abundance of Methanosaeta by 3%-10%, doubled the protein content in extracellular polymeric substances, and boosted the expression of cytochrome c-related genes, thereby enhancing direct electron transfer capacity. These findings present a novel and efficient approach for constructing a stable, high-performance biocathode, contributing to energy recovery and CO2 fixation.

中文翻译：

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增强微生物电合成中的 CO2 还原甲烷生成：含氧基团对碳基阴极的作用


微生物电合成是一项很有前途的技术，它可以从废水中回收能量，同时将 CO2 转化为 CH4。构建具有强大的 H2 介导和直接电子转移能力的生物阴极面对于高效启动和长期稳定的 CH4 生产至关重要。本研究发现，将羧基引入阴极有效地增强了两种电子转移途径，提高了 CH4 产生的还原速率和库仑效率，并将 CH4 产率提高了 2-3 倍。羧基降低了 H2 析出的过电位并增加了电流密度，从而增强了 H2 介导的电子转移。此外，羧基使 Methanosaeta 的相对丰度增加了 3%-10%，使细胞外聚合物中的蛋白质含量增加了一倍，并促进了细胞色素 c 相关基因的表达，从而增强了直接电子转移能力。这些发现为构建稳定、高性能的生物阴极面提供了一种新颖有效的方法，有助于能量回收和 CO2 固定。