The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, 118 Dana Hall Spokane St. P.O. Box 642710, Pullman, WA 99164-2710, USA.
Phys Chem Chem Phys. 2011 Dec 28;13(48):21573-84. doi: 10.1039/c1cp23200b. Epub 2011 Nov 3.
Sediment microbial fuel cells (SMFCs) have been used as renewable power sources for sensors in fresh and ocean waters. Organic compounds at the anode drive anodic reactions, while oxygen drives cathodic reactions. An understanding of oxygen reduction kinetics and the factors that determine graphite cathode performance is needed to predict cathodic current and potential losses, and eventually to estimate the power production of SMFCs. Our goals were to (1) experimentally quantify the dependence of oxygen reduction kinetics on temperature, electrode potential, and dissolved oxygen concentration for the graphite cathodes of SMFCs and (2) develop a mechanistic model. To accomplish this, we monitored current on polarized cathodes in river and ocean SMFCs. We found that (1) after oxygen reduction is initiated, the current density is linearly dependent on polarization potential for both SMFC types; (2) current density magnitude increases linearly with temperature in river SMFCs but remains constant with temperature in ocean SMFCs; (3) the standard heterogeneous rate constant controls the current density temperature dependence; (4) river and ocean SMFC graphite cathodes have large potential losses, estimated by the model to be 470 mV and 614 mV, respectively; and (5) the electrochemical potential available at the cathode is the primary factor controlling reduction kinetic rates. The mechanistic model based on thermodynamic and electrochemical principles successfully fit and predicted the data. The data, experimental system, and model can be used in future studies to guide SMFC design and deployment, assess SMFC current production, test cathode material performance, and predict cathode contamination.
沉积物微生物燃料电池 (SMFC) 已被用作淡水和海水中传感器的可再生电源。阳极处的有机化合物驱动阳极反应，而氧气则驱动阴极反应。为了预测阴极电流和电位损耗，最终估计 SMFC 的发电能力，需要了解氧气还原动力学以及决定石墨阴极性能的因素。我们的目标是：(1) 实验量化 SMFC 石墨阴极的氧气还原动力学对温度、电极电位和溶解氧浓度的依赖关系；(2) 开发一个机械模型。为了实现这一目标，我们监测了河流和海洋 SMFC 中极化阴极的电流。我们发现：(1) 在氧气还原开始后，两种 SMFC 类型的电流密度与极化电位呈线性相关；(2) 河流 SMFC 中的电流密度随温度呈线性增加，但海洋 SMFC 中的电流密度随温度保持不变；(3) 标准非均相速率常数控制电流密度的温度依赖性；(4) 河流和海洋 SMFC 石墨阴极的电位损耗较大，模型估计分别为 470 mV 和 614 mV；(5) 阴极的电化学势是控制还原动力学速率的主要因素。基于热力学和电化学原理的机械模型成功拟合和预测了数据。这些数据、实验系统和模型可用于未来的研究，以指导 SMFC 的设计和部署、评估 SMFC 的电流产生、测试阴极材料的性能以及预测阴极污染。
