Effect of sediment embedding ratio on the cathode electrochemical performance in marine microbial fuel cells on ocean floor

沉积物掩埋程度对海洋微生物燃料电池阴极电化学性能的影响

¹ School of Materials Science and Engineering, Ocean University of China, Qingdao 266100, China
² School of Environment Science and Engineering, Ocean University of China, Qingdao 266100, China

Received: 27 January 2021

Abstract

In the long-term electricity generation and driving sensor work process of marine sediment microbial fuel cells(MSMFCs), its cathode in the seawater may be embedded into the marine sediment, which will affect the electrochemical performance and lead to MSMFCs failure. The article simulated the embedding ratio of cathodes in sediment in the laboratory: 1/3, 1/2, 2/3, in order to investigate the changes of the electrochemical performance of the cathode and the electricity generation performance of MSMFCs. The results show that: the open circuit potential dropped and the required longer steady time with the higher embedding ratio of the cathode. Its capacitance decreased gradually, and the minimum capacitance was 32 F/cm² (2/3 group), which was 0.72 times of the Blank. The kinetic activity decreased firstly and then increased, and its maximum activity was 1.61 times of the Blank (2/3 group); The maximum power density of the MSMFCs was 140.83 mW/m² (1/3 group), which was 1.21 times of the Blank. With the increase of embedding ratio of the cathode in the marine sediment, its electrochemical performance and electricity generation performance of MSMFCs both fluctuates, but the normal operation of MSMFCs can still be ensured.

摘要

海洋沉积物微生物燃料电池(MSMFCs)在海底产电并长期驱动传感器运行过程中, 悬浮于水体中阴极易被海底沉积物掩埋从而影响产电性能, 导致电池失效。在实验室中模拟沉积物分别掩埋1/3, 1/2和2/3电池阴极, 探究阴极电化学性能和电池产电规律。结果表明: 随着阴极被沉积物掩埋程度增加, 开路电位逐渐降低, 而需要稳定的时间增加; 阴极电容逐渐减小, 最小电容降至32 F/cm², 是未掩埋对照组的0.72倍; 动力学活性先降后升, 最大活性为对照组的1.61倍(2/3组)。掩埋过程中, MSMFCs产电性能未受影响, 最大功率密度达140.83 mW/m²(1/3组), 是对照组的1.21倍。可见, 随着阴极被海底沉积物掩埋程度的增加, 尽管阴极电化学性能下降、电池产电性能出现波动, 但MSMFCs仍可正常工作。