微生物燃料电池非生物阴极催化剂的研究进展

在微生物燃料电池（MFC）中,以氧为电子受体具有很多优点,但氧阴极还原的反应动力学慢,会造成阴极电势的损失。 因此,提高阴极对氧还原的电催化活性和降低催化剂的价格是MFC非生物阴极催化剂的研究重点之一。 本文综述了近年来MFC中非生物阴极氧还原催化剂的研究进展。 重点讨论了贵金属Pt、过渡金属大环化合物以及金属氧化物催化剂对氧还原的电催化活性。 其中,非贵金属氧化物及过渡金属大环化合物催化剂具有良好的性能,而且价格低廉,有望成为MFC非生物阴极Pt基催化剂的替代催化剂。     

Power generation using an activated carbon and metal mesh cathode in a microbial fuel cell

An inexpensive activated carbon (AC) air cathode was developed as an alternative to a platinum-catalyzed electrode for oxygen reduction in a microbial fuel cell (MFC). AC was cold-pressed with a polytetrafluoroethylene (PTFE) binder to form the cathode around a Ni mesh current collector. This cathode construction avoided the need for carbon cloth or a metal catalyst, and produced a cathode with high activity for oxygen reduction at typical MFC current densities. Tests with the AC cathode produced a maximum power density of 1220 mW/m² (normalized to cathode projected surface area; 36 W/m³ based on liquid volume) compared to 1060 mW/m² obtained by Pt catalyzed carbon cloth cathode. The Coulombic efficiency ranged from 15% to 55%. These findings show that AC is a cost-effective material for achieving useful rates of oxygen reduction in air cathode MFCs.     

Development of Apple Tissue Based Biocathode and MWCNT−Pt−Au Nanomaterial Based Bioanode Biofuel Cell

A biofuel cell (BFC) was fabricated by combining multiwalled carbon nanotube -platinum-gold (MWCNT−Pt−Au) hybrid nanomaterial, glucose oxidase (GOx) and benzoquinone included carbon felt electrode (CFE) bioanode with apple tissue included CFE biocathode. The working parameters of bioanode were optimized both experimentally and chemometrically. For the biocathode, apple, banana and pear tissues were tried and best power output was obtained with apple tissue. By combining MWCNT−Pt−Au/GOx/CFE bioanode with apple tissue based biocathode, single cell, double cell with membrane and with salt-bridge BFCs were formed. The best power output with highest current density were obtained with single cell BFC.     

不锈钢网阴极微生物燃料电池的产电性能研究

构建了一个以曝气池污泥为阳极接种微生物、碳毡为阳极、无任何修饰的不锈钢网为阴极的双室微生物燃料电池. 通过输出电压、功率密度以及电化学阻抗等考察了阴极面积对电池产电性能的影响,并对电池的长期运行稳定性进行评价. 研究结果表明,不锈钢网作为微生物燃料电池的阴极性能稳定. 当不锈钢网面积为2 × 2 cm²时,最大输出电压达到0.411 V,功率密度为0.303 W•m^-2,内阻841 Ω,极化内阻80 Ω. 增大阴极面积至2 × 4 cm²,最大输出电压能达到0.499 V,内阻减小至793 Ω. 不锈钢网价格便宜,具有长期运行稳定性,适宜做MFCs的阴极.     

Degradation Investigation of Electrocatalyst in Proton Exchange Membrane Fuel Cell at a High Energy Efficiency

The development of high efficient stacks is critical for the wide spread application of proton exchange membrane fuel cells (PEMFCs) in transportation and stationary power plant. Currently, the favorable operation conditions of PEMFCs are with single cell voltage between 0.65 and 0.7 V, corresponding to energy efficiency lower than 57%. For the long term, PEMFCs need to be operated at higher voltage to increase the energy efficiency and thus promote the fuel economy for transportation and stationary applications. Herein, PEMFC single cell was investigated to demonstrate its capability to working with voltage and energy efficiency higher than 0.8 V and 65%, respectively. It was demonstrated that the PEMFC encountered a significant performance degradation after the 64 h operation. The cell voltage declined by more than 13% at the current density of 1000 mA cm⁻², due to the electrode de-activation. The high operation potential of the cathode leads to the corrosion of carbon support and then causes the detachment of Pt nanoparticles, resulting in significant Pt agglomeration. The catalytic surface area of cathode Pt is thus reduced for oxygen reduction and the cell performance decreased. Therefore, electrochemically stable Pt catalyst is highly desirable for efficient PEMFCs operated under cell voltage higher than 0.8 V.     

Microbial fuel cell-based self-powered biosensing platform for determination of ketamine as an anesthesia drug in clinical serum samples

A novel self-powered DNA biosensor was successfully developed based on a dual-chambered microbial fuel cell (MFC) apparatus as a power supply and ketamine (KET) as a hybridization indicator. A graphite electrode coated with gold nanoparticles (GNP/graphite electrode), which provided larger surface area for immobilization of thiolated single-stranded (ssDNA) probe, was used as biocathode in the MFC system. When KET was used as the hybridization indicator for detection of ssDNA probe, the indicator exhibited excellent selectivity in detecting and discriminating the complementary, single-base mismatched, and noncomplementary target sequences. Furthermore, this self-powered biosensor based on MFC apparatus served as the biosensing platform for determination of KET in clinical serum samples. Under the steady-state operation condition, the difference between power densities of the ssDNA probe-modified GNP/graphite cathode in the absence and presence of accumulated KET (ΔP) served as the detection signal with a detection limit of 0.54 nM. The proposed MFC-based self-powered biosensor, as a low-cost portable device, showed a high sensitivity, stability, and reproducibility. Therefore, it can become a promising platform for determination of KET in clinical researches.     

空气阴极生物燃料电池电化学性能

为提高生物燃料电池(MFC)的输出功率, 降低内阻和有机物处理成本, 实验以空气电极为阴极, 泡沫镍(铁)为阳极,葡萄糖模拟废水为基质构建了直接空气阴极单室生物燃料电池, 考察了电池的电化学性能. 结果表明, MFC的开路电压为0.62 V, 内阻为33.8 Ω, 最大输出功率为700 mW·m-2 (4146 mW·m-3污水), 电子回收率20%. 放电曲线、循环伏安测试表明, MFC首次放电比容量和比能量分别为263 mAh·g-1 COD(化学需氧量)和77.3 mWh·g-1 COD, MFC充放电性能及稳定性均较好. 电化学交流阻抗谱(EIS)分析表明, 随放电时间的延长, 电池阻抗增大, 这是导致电池输出电压逐渐降低的原因之一. MFC运行8 h, COD的去除率为56.5%, 且COD的降解符合表观一级反应动力学.     

Lead dioxide as an alternative catalyst to platinum in microbial fuel cells

Lead dioxide (PbO₂) was compared to platinum (Pt) as a cathode catalyst in a double-cell microbial fuel cell (MFC) utilizing glucose as a substrate in the anode chamber. Four types of cathodes were tested in this study including two PbO₂ cathodes fabricated using a titanium base with butanol or Nafion^® binders and PbO₂ paste, one Pt/carbon cathode fabricated using a titanium base with a carbon–Pt paste, and a commercially available Pt/carbon cathode made from carbon paper with Pt on one side. The power density and polarization curves were compared for each cathode and cost estimates were calculated. Results indicate the PbO₂ cathodes produced between 2 and 4× more power than the Pt cathodes. Furthermore, the PbO₂ cathodes produced between 2 and 17× more power per initial fabrication or purchase cost than the Pt cathodes. This study suggests that cathode designs that incorporate PbO₂ instead of Pt could possibly improve the feasibility of scaling up MFC designs for real world applications by improving power generation and lowering production cost.     

Microbial Fuel Cells: The Effects of Configurations,Electrolyte Solutions,and Electrode Materials on Power Generation

This objective of this study is to conduct a systematic investigation of the effects of configurations, electrolyte solutions, and electrode materials on the performance of microbial fuel cells (MFC). A comparison of voltage generation, power density, and acclimation period of electrogenic bacteria was performed for a variety of MFCs. In terms of MFC configuration, membrane-less two-chamber MFCs (ML-2CMFC) had lower internal resistance, shorter acclimation period, and higher voltage generation than the conventional two-chamber MFCs (2CMFC). In terms of anode solutions (as electron donors), the two-chamber MFCs fed with anaerobic treated wastewater (AF-2CMFCs) had the power density 19 times as the two-chamber MFCs fed with acetate (NO₃ ⁻2CMFCs). In terms of cathode solutions (as electron acceptors), AF-2CMFCs with ferricyanide had higher voltage generation than that of ML-2CMFCs with nitrate (NO₃ ⁻ML-2CMFCs). In terms of electrode materials, ML-2CMFCs with granular-activated carbon as the electrode (GAC-ML-2CMFCs) had a power density 2.5 times as ML-2CMFCs with carbon cloth as the electrode. GAC-ML-2CMFCs had the highest columbic efficiency and power output among all the MFCs tested, indicating that the high surface area of GAC facilitate the biofilm formation, accelerate the degradation of organic substrates, and improve power generation.     

微生物燃料电池生物阴极

微生物燃料电池(microbial fuel cells, MFCs)利用微生物处理废水的同时产电,是一种清洁可再生能源技术。近年来新兴起的生物阴极是指阴极室中的功能微生物附着在电极表面形成生物膜,电子由电极传递给微生物并发生相应的生物电化学反应;是微生物燃料电池研究的一个重要方向。本文根据厌氧、好氧操作体系的不同将生物阴极进行分类;归纳总结了微生物组成、电极和分隔材料的研究进展,探讨了生物阴极在去除污染物和生成高附加值产品中的实际应用,并提出了其将来发展的可能方向。     

固酶氮掺杂碳纳米复合物基燃料电池性能

利用掺杂氮介孔材料(NDMPC)和羧甲基壳聚糖(CMCH)机械共混的纳米复合物作为固酶载体,以滴涂-干燥法分别制备了固定漆酶(Lac)阴极和固定葡萄糖氧化酶阳极,组装了有Nafion离子交换膜的葡萄糖/O₂酶燃料电池.固定漆酶电极作为燃料电池阴极和氧电化学传感器的性能以结合旋转圆盘电极技术的循环伏安法、线性扫描伏安(LSV)法以及计时电流法进行表征,同时使用紫外-可见分光光度法和石墨炉原子吸收光谱法研究酶分子在电极表面的构型和估算电极表面载体对酶的担载量.测试结果表明:固酶阴极在无电子中介体时可以实现漆酶活性中心T₁与导电基体之间的直接电子迁移(表观电子迁移速率为0.013 s^-1),而且具有较小的氧还原超电势(150 mV).通过进一步定量比较分子内电子传递速率(1000 s^-1)、底物转化速率(0.023 s^-1)以及前述酶-导电基体间电子迁移速率,可以发现此电极催化氧还原循环受制于酶-电极之间的电子迁移过程;这种电极对氧的传感性能良好:低检测限(0.04 μmol·dm^-3)、高灵敏度(12.1 μA·μmol^-1·dm³)和良好的对氧亲和力(K_M = 8.2 μmol·dm^-3),这种固酶阴极还具有良好的重现性、长期使用性、热稳定性和pH耐受性.组装的生物燃料电池的开路电压为0.38 V,最大能量输出密度为19.2 μW·cm^-2,最佳工作条件下使用3周后输出功率密度仍可保持初始值的60%以上.     

Effects of different Pt-M (M = Fe,Co, Ni) alloy as cathodic catalyst on the performance of two-chambered microbial fuel cells

For the purpose of reducing the cost and improving the performance of cathodes in microbial fuel cells (MFCs), we prepared Pt/C and Pt-M/C (M = Ni, Co, Fe) electrodes, and characterized them by SEM, XRD and CV. The modified electrodes were used as the cathodes in double-chambered MFCs fed with synthetic medium and molasses sewage respectively. We have found that Pt-M/C catalysts had a better catalytic activity for oxygen reduction than Pt/C in the following order: Pt-Fe/C > Pt-Co/C > Pt-Ni/C > Pt/C. The maximum power density of the MFCs with Pt-M/C cathode was improved by 18–31% compared with the MFC with Pt/C cathode because of the decrease of activation loss in the cathode. This study shows that Pt-M/C catalysts can improve power generation of MFCs without affecting the COD removal and it is proposed that Pt-Fe functions best among the three Pt-M alloys as an efficient and cost-effective catalyst of MFCs.     

Cobalt‐based Catalysts Modified Cathode for Enhancing Bioelectricity Generation and Wastewater Treatment in Air‐breathing Cathode Microbial Fuel Cells

To seek an efficient way to enhance the power output and wastewater treatment of microbial fuel cell (MFC), several cobalt‐based composites are successfully synthesized by a facile hydrothermal method under different pyrolysis temperature, and these composites are used as electrocatalyst in air‐breathing cathode of MFC. Different species of nitrogen atom are successfully grafted on the cobalt‐based composites and confirmed by physical and electrochemical analyses. In MFC tests, the maximum power density increases from 577.8 mW m^?2 to 931.1 mW m^?2 with pyrolysis temperature (except for 1000 °C). These electrochemical tests and high COD removal show that Co/N/C‐900 can rapidly transfer electron via a 2×2 e^? transfer pathway, mainly due to the exposure of large electrochemical active area and introduction of the defects of pyridinic?N and abundant oxygen vacancies. Although the power density of MFC with Co/N/C‐900 is 81.1 % of that of commercial Pt/C, the MFC with Co/N/C‐900 is more stable than that of Pt/C, and the power density for Co/N/C‐900 has only a 2.8 % decrease during 25‐cycles operation. The great electrocatalytic activity of the novel Co/N/C‐900 composite exhibits a superior outlook for scale‐up application of MFC in the future.     

Biotic Cathode of Graphite Fibre Brush for Improved Application in Microbial Fuel Cells

The biocathode in a microbial fuel cell (MFC) system is a promising and a cheap alternative method to improve cathode reaction performance. This study aims to identify the effect of the electrode combination between non-chemical modified stainless steel (SS) and graphite fibre brush (GFB) for constructing bio-electrodes in an MFC. In this study, the MFC had two chambers, separated by a cation exchange membrane, and underwent a total of four different treatments with different electrode arrangements (anodeǁcathode)—SSǁSS (control), GFBǁSS, GFBǁGFB and SSǁGFB. Both electrodes were heat-treated to improve surface oxidation. On the 20th day of the operation, the GFBǁGFB arrangement generated the highest power density, up to 3.03 W/m³ (177 A/m³), followed by the SSǁGFB (0.0106 W/m³, 0.412 A/m³), the GFBǁSS (0.0283 W/m³, 17.1 A/m³), and the SSǁSS arrangements (0.0069 W/m⁻³, 1.64 A/m³). The GFBǁGFB had the lowest internal resistance (0.2 kΩ), corresponding to the highest power output. The other electrode arrangements, SSǁGFB, GFBǁSS, and SSǁSS, showed very high internal resistance (82 kΩ, 2.1 kΩ and 18 kΩ, respectively) due to the low proton and electron movement activity in the MFC systems. The results show that GFB materials can be used as anode and cathode in a fully biotic MFC system.     

The use of electrochemical impedance spectroscopy (EIS) in the evaluation of the electrochemical properties of a microbial fuel cell

Electrochemical impedance spectroscopy (EIS) has been used to determine several electrochemical properties of the anode and cathode of a mediator-less microbial fuel cell (MFC) under different operational conditions. These operational conditions included a system with and without the bacterial catalyst and EIS measurements at the open-circuit potential of the anode and the cathode or at an applied cell voltage. In all cases the impedance spectra followed a simple one-time-constant model (OTCM) in which the solution resistance is in series with a parallel combination of the polarization resistance and the electrode capacitance. Analysis of the impedance spectra showed that addition of Shewanella oneidensis MR-1 to a solution of buffer and lactate greatly increased the rate of the lactate oxidation at the anode under open-circuit conditions. The large decrease of open-circuit potential of the anode increased the cell voltage of the MFC and its power output. Measurements of impedance spectra for the MFC at different cell voltages resulted in determining the internal resistance (R(int)) of the MFC and it was found that R(int) is a function of cell voltage. Additionally, R(int) was equal to R(ext) at the cell voltage corresponding to maximum power, where R(ext) is the external resistance that must be applied across the circuit to obtain the maximum power output.     

Performance enhancement of phosphoric acid-based proton exchange membrane fuel cells by using ammonium trifluoromethanesulfonate

In a fuel cell system where concentrated phosphoric acid (PA) is used as a proton conducting medium, the use of PA causes some undesirable effects on oxygen reduction reaction (ORR) at Pt catalyst. Ammonium trifluoromethanesulfonate (ATFMS) is introduced as a cathode additive to increase the local oxygen concentration near the Pt catalyst. A cathode with the optimum composition of ATFMS shows a higher single cell performance than that without the additive when a single cell based on a PA-doped polymer membrane is operated at 150 °C. The enhanced ORR activity and oxygen solubility with the incorporation of ATFMS are proved with rotating disk electrode (RDE) and Pt microelectrode experiments. Single cell performance for longer than 600 h without decay in operating voltage could support the stability of the additive.     

Intermittent operation of the aprotic Li-O2 battery: the mass recovery process upon discharge interval

The intermittent operation of the aprotic Li-O₂ battery is systematically studied in this paper. A combined study of the battery charge retention and the electrolyte stability to O₂ suggests a low self-discharge rate of the Li-O₂ battery, which is a prerequisite to achieve desirable intermittent discharge performance. The battery under intermittent operation exhibits significantly improved discharge performance as compared to the continuously discharged one. It is found that the capacity output is directly associated with the time interval between two discharge steps and with the capacity limit for each discharge step. The open-circuit potential and linear scan voltammetry analyses confirm that a “mass recovery” process, corresponding to the concentration relaxation of the oxygen which is available at the cathode, proceed during the discharge intervals. In the “mass recovery” process, an increased amount of O₂ homogeneously redistributes at the electrolyte/carbon interface at both sides of the electrode, which relieves the O₂ transport limit, enhances the availability of O₂ and the utilization of carbon material for the cathode, and thus significantly improves the discharge performance of the aprotic Li-O₂ battery.     

Poly(vinyl alcohol) separators improve the coulombic efficiency of activated carbon cathodes in microbial fuel cells

High-performance microbial fuel cell (MFC) air cathodes were constructed using a combination of inexpensive materials for the oxygen reduction cathode catalyst and the electrode separator. A poly(vinyl alcohol) (PVA)-based electrode separator enabled high coulombic efficiencies (CEs) in MFCs with activated carbon (AC) cathodes without significantly decreasing power output. MFCs with AC cathodes and PVA separators had CEs (43%–89%) about twice those of AC cathodes lacking a separator (17%–55%) or cathodes made with platinum supported on carbon catalyst (Pt/C) and carbon cloth (CE of 20%–50%). Similar maximum power densities were observed for AC-cathode MFCs with (840 ± 42 mW/m²) or without (860 ± 10 mW/m²) the PVA separator after 18 cycles (36 days). Compared to MFCs with Pt-based cathodes, the cost of the AC-based cathodes with PVA separators was substantially reduced. These results demonstrated that AC-based cathodes with PVA separators are an inexpensive alternative to expensive Pt-based cathodes for construction of larger-scale MFC reactors.     

Design of Clayware Separator-Electrode Assembly for Treatment of Wastewater in Microbial Fuel Cells

Performance of six different microbial fuel cells (MFCs) made from baked clayware, having 450 ml effective anodic chamber volume, was evaluated, with different configurations of separator electrode assemblies, to study the feasibility of bioelectricity generation and high-strength wastewater treatment in a single-chambered mediator-less air-cathode MFC. Superior performance of an air-cathode MFC (ACMFC) with carbon coating on both sides of the separator was observed over an aqueous cathode MFC, resulting in a maximum volumetric power of 4.38 W m^?3 and chemical oxygen demand (COD) removal efficiency of more than 90 % in a batch cycle of 4 days. Hydrophilic polymer polyvinyl alcohol (PVA) was successfully used as a binder. The problem of salt deposition and fouling of cathode could be minimized by using a sock net current collector, replacing the usual stainless steel wire. However, electrolyte loss due to evaporation is a problem that needs to be resolved for better performance of an ACMFC.     

阴极催化剂对微生物燃料电池性能的影响

以不同载量的MnO_2/rGO和Pt/C修饰阴极电极构建了生物阴极型双室微生物燃料电池(MFC),考察了不同阴极催化剂修饰MFC对其产电性能以及老龄垃圾渗滤液主要污染物去除效果的影响。结果表明,以MnO_2/rGO修饰MFC阴极电极材料,能显著提高MFC产电性能及对老龄垃圾渗滤液中污染物去除效果;输出电压为372 mV,功率密度为194 mW/m~3(是未经催化剂修饰MFC的两倍),内阻为264Ω,化学需氧量(COD)和氨氮(NH_3-N)去除率分别为58.68%和76.64%。当MnO_2/rGO载量为.0 mg/cm~2时,MFC性能与负载Pt/C的MFC性能接近,但构建成本却明显降低。