Cu2O/rGO复合材料修饰阴极强化MFC产电脱氮性能及其机理

微生物燃料电池(MFC)在处理含硝酸盐(NO_3^--N)废水时具有同时产电和脱氮的潜力,寻找成本低且改善其产电脱氮性能的阴极修饰材料是MFC在含氮废水处理领域应用的关键。氧化亚铜/还原氧化石墨烯(Cu₂O/rGO)复合材料具有良好的电化学性能,在替代铂基材料提高MFC性能方面具有一定的应用前景。本研究通过还原法制备了Cu₂O/rGO复合材料,并对材料的结构和氧还原性能进行表征；同时,将其负载于阴极碳布后分析其电化学性能,并通过MFC的输出电压、功率密度和NO_3^--N的去除率探究Cu₂O/rGO阴极对MFC产电和脱氮性能的强化作用；通过对反硝化相关酶活性和胞外聚合物的测定,探究Cu₂O/rGO阴极强化MFC性能的机理。结果表明：Cu₂O/rGO复合材料具有大量的介孔结构,能够为电子传递提供更多的通道,并且Cu₂O/rGO复合材料具有良好的氧化还原可逆性；与Pt/C阴极相比,Cu₂O/rGO阴极的交换电流密度升高33.53%,电子转移阻力降低65.53%；Cu₂O/rGO-MFC在处理NO_3^-N废水时获得的最大平均输出电压(662.54 mV)、最大功率密度(26.27 mW/cm^₂)、平均库伦效率(32.02%)和NO_3^--N去除速率(83.33 mg NO_3^--N L/h)均高于Pt/C-MFC(485.33 mV,16.98 mW/cm^₂,7.38%,41.67 mg NO_3^--N L/h)；Cu₂O/rGO复合材料通过提高MFC阴极反硝化关键酶活性和类蛋白组分含量,改善了MFC的产电和脱氮性能。

Mechanism of Cu2O/rGO cathode catalyst enhances the electricity production and nitrogen removal of MFC

Microbial fuel cells (MFC) have the potential of generating electricity and removing nitrogen simultaneously in the treatment of nitrate containing wastewater. It is crucial to find a cathode modified material with low cost and improved performance of generating electricity and removing nitrogen for the commercial application of MFC in the field of wastewater treatment. Cuprous oxide/reduced graphene oxide (Cu₂O/rGO) composite which has the advantages of excellent electrochemical properties, hold a wide application prospect in replace of Pt-based material for improving performance of microbial fuel cells (MFCs). In this study, material characterization and oxygen reduction property were conducted to analyze the synthesis of Cu₂O/rGO composite materials after synthesis by reduction method. The electrochemical performance of Cu₂O/rGO cathode was analyzed after it was loaded on the surface of cathode carbon cloth. The enhancement effect of Cu₂O/rGO cathode on the power generation and nitrogen removal performance of MFC were investigated through the output voltage, power density and NO_3^--N removal rate of MFC. The mechanism of Cu₂O/rGO cathode enhancing MFC performance was investigated by measuring denitrifying enzyme activity and extracellular polymer. Results showed that Cu₂O/rGO which has a large number of mesoporous structures, provide more channels for electron transport, and Cu₂O/rGO has better redox reversibility. Compared with Pt/C cathode, the exchange current density of Cu₂O/rGO cathode increases by 33.53%, the electron transfer resistance decreases by 65.53%. The maximum average output voltage (662.54 mV), maximum power density (26.27 mW/cm^₂), NO_3^--N removal rate (83.33 mg NO_3^--N L/h) and average coulomb efficiency (32.02%) of Cu₂O/rGO-MFC were higher than those of Pt/C-MFC (485.33 mV, 16.98 mW/cm^₂, 7.38%, 41.67 mg NO_3^--N L/h). Cu₂O/rGO composite material enhance the activity of key enzymes and the content of protein-like components in denitrification of MFC cathode, improving the performance of electricity generation and nitrogen removal of Cu₂O/rGO-MFC.