硝酸-PPy/AQDS联合处理改善阳极性能的分析表征

阳极性能是影响微生物燃料电池(microbial fuel cells,MFCs)性能的关键因素之一.通过吡咯聚合、蒽醌-2,6-磺酸钠盐(AQDS)掺杂以及库仑量调控将不同厚度的PPy/AQDS复合薄膜电沉积至硝酸处理的碳毡阳极上,以期整合碳毡阳极的生物亲合性、导电性及电子传递能力,同时强化阳极的这3种性能.结果表明,随着整合强度的加强,阳极性能逐步得到提升,整合阳极在阳极生物量、电导率以及交换电流密度方面优于对照组2.4~3.3倍,其中0.12 C·cm~(-2)的整合阳极表现出最高的峰值电流(2.86 m A)、最大的阳极生物量(0.44 mg·cm-2)、最大的电导率(0.33 S·cm~(-1))、最大的交换电流密度(3.65×10~(-3)A·m~(-2))以及最小的传质阻力,其对应MFC的最大功率密度达1 060.7 m W·m~(-2),是对照组的2.2倍,阳极开路电势接近-0.55V.循环伏安、电化学阻抗谱、扫描电镜和塔菲尔测试进一步揭示了PPy/AQDS复合薄膜在阳极碳纤维之间的联接、架桥作用,使得不同纤维丝之间的接触更加均匀,减小了电子在生物膜与阳极之间、阳极与外回路之间的传递阻力;同时,沉积于碳毡阳极的PPy/AQDS复合薄膜与硝酸处理后阳极表面形成的吡咯氮类官能团之间的协同作用可能是整合阳极性能提升的本质原因所在.

Analysis and Characterization of Multi-modified Anodes via Nitric Acid and PPy/AQDS in Microbial Fuel Cells

The properties of anode material are crucial for high performances in microbial fuel cells (MFCs). Hereby, a biocompatible, conductive, and high electron transfer ability anode was fabricated by electrodepositing polypyrrole/anthraquinone-2, 6-disulphonic disodium salt (PPy/AQDS) onto nitric acid-soaked carbon felt. The results showed that the multi-modified anode outperformed the pristine one in biomass, electrical conductivity, and exchange current density with between 2.4 and 3.3 times better performance. The multi-modified anode (applied with 0.12 C·cm^-2 total charge density) showed the highest peak current density (2.86 mA), the largest amount of biomass loading (0.44 mg·cm^-2), the most favoured electrical conductivity (0.33 S·cm^-1), and exchange current density (3.65×10^-3 A·m^-2), as a result, the maximum power density of the MFC equipped with the anode delivered a 2.2-fold increase over that of the control (1060.7 mW·m^-2 vs. 477.6 mW·m^-2), and thus has great potential to be used as an anode for high-power MFCs. Further investigation revealed that the increased energy output might be attributed to the bridging of the carbon fibers by electrically conductive PPy/AQDS composite films, which provided a uniform connection throughout the nitric treated carbon felt as well as the synergetic effects between the newly formed functional groups like pyrrolic N and PPy/AQDS. It was proposed that integrating biocompatibility (BCB) with electrical conductivity (EC) and electron transfer efficiency (ETE) through multi-modification could form high-performance anode. Future efforts to be made for realizing more extraordinary high-performance MFCs anodes were also outlined. This work may also provide a novel universal approach for the development of other types of anode for high-performance MFCs through integrating the BCB with EC and ETE simultaneously.