微生物燃料电池MnO_2/S-AC泡沫镍空气阴极的制备及其性能

Preparation and properties of nickel foam air cathode with MnO_2/S-AC catalyst for microbial fuel cells

利用超级电容器活性炭(S-AC)直接还原KMnO4制备出复合比例分别为1:3、1:1和3:1的MnO2/S-AC复合催化剂,进而负载于泡沫镍上制得MnO2/S-AC泡沫镍空气阴极。通过X射线衍射(XRD)、扫描电镜(SEM)、能量散射X射线谱(EDX)和比表面积(BET)及孔分布测试对所制复合催化剂表征可知,随复合比例的增加,在S-AC表面的MnO2由纳米薄片聚集成粒径为300~500nm的颗粒,MnO2/S-AC的内部及外部表面积都有所减少。基于线性扫描伏安曲线、功率密度曲线和极化曲线分析微生物燃料电池(MFC)的阴极性能和产电性能。复合比例为1:3时,MFC最大功率密度达到321.2mW·m-2,比阴极负载S-AC时提高了约20%,这与其较高的比表面积和MnO2良好的催化活性相关。MnO2/S-AC复合催化剂控制在一定的质量比时,可以有效提高阴极性能及MFC的产电效果,有助于空气阴极MFC的的放大和工程应用。

The kinetics of oxygen reduction of cathode catalyst is a critical factor that limits the performance of microbial fuel cells (MFCs). The composite catalyst of three composite proportion(1:3, 1:1 and 3:1), which were prepared by reacting KMnO4 with supercapacitor activated carbon (S-AC),were tested as air-cathode catalyst of microbial fuel cells (MFCs) for oxygen reduction. X-ray diffraction (XRD) was used to characterize the catalysts, energy dispersive X-Ray Spectroscopy to estimate the quality of MnO2, scanning electron microscopy (SEM) to observe the surface morphology, and BET method to examine surface area and pore distribution characteristics, to analyze the factors affecting the performance of the composite catalyst. With increasing of composite proportion, the MnO2 sheets gathered into nano-particles (300-500 nm) on the surface of S-AC. At the same time, there is the decrease of the internal and external surface area MnO2/S-AC. Nickel foam air-cathode was made with different catalysts, and tested in air-cathode MFCs to study the effect on MFC performance by linear sweep voltammetry (LSV), polarization curves and power density curve. When the feeding ratio of KMnO4: S-AC is 1:3,the maximum power density was 321.2 mW·m?2, which was increased by about 20% over the S-AC loading MFC. However, when the feeding ratio was increased to 1:1 and 3:1, the maximum power density decreased to 240.9 and 160.3 mW·m?2. MnO2/S-AC composite catalyst within a certain ratio range could effectively improve the performance of air-cathode and MFC, which helps to the expansion application of air-cathode MFC.