微生物燃料电池阳极改性修饰最新研究进展

阳极是影响微生物燃料电池性能的重要因素之一,开发简易、高效的阳极改性修饰方法对微生物燃料电池的实际应用具有关键作用。对目前微生物燃料电池阳极改性修饰的最新进展展开综述,总结了分析阳极材料的方法,并对阳极修饰方法未来发展趋势进行了展望。     

Marine microbial fuel cell: Use of stainless steel electrodes as anode and cathode materials

Numerous biocorrosion studies have stated that biofilms formed in aerobic seawater induce an efficient catalysis of the oxygen reduction on stainless steels. This property was implemented here for the first time in a marine microbial fuel cell (MFC). A prototype was designed with a stainless steel anode embedded in marine sediments coupled to a stainless steel cathode in the overlying seawater. Recording current/potential curves during the progress of the experiment confirmed that the cathode progressively acquired effective catalytic properties. The maximal power density produced of 4 mW m⁻² was lower than those reported previously with marine MFC using graphite electrodes. Decoupling anode and cathode showed that the cathode suffered practical problems related to implementation in the sea, which may found easy technical solutions. A laboratory fuel cell based on the same principle demonstrated that the biofilm-covered stainless steel cathode was able to supply current density up to 140 mA m⁻² at +0.05 V versus Ag/AgCl. The power density of 23 mW m⁻² was in this case limited by the anode. These first tests presented the biofilm-covered stainless steel cathodes as very promising candidates to be implemented in marine MFC. The suitability of stainless steel as anode has to be further investigated.     

微生物燃料电池纳米纤维基阳极材料的研究进展

微生物燃料电池（Microbial fuel cell，MFC）是一种非常有前途的环境友好型电化学装置，它可以利用电活性微生物从废水中提取能源，并降解废水中的有机物，是解决目前环境与能源危机的重要技术。然而，相对较低的产电效率限制了其大规模应用，主要体现在阳极缓慢的胞外电子传递速率（extracellular electron transfer，EET）和较少的产电微生物附着量。纳米纤维由于具有高的比表面积、良好的电化学性能和电导率，是改善阳极的重要材料。本文介绍了影响阳极材料性能的因素，系统总结了近年来国内外纳米纤维基阳极材料的种类与制备方法，针对纳米纤维基阳极材料在MFC领域的研究现状，重点解释了各种纳米纤维材料的优缺点。最后，对纳米纤维基电极材料以及MFC技术的发展方向进行了展望，以期为推动MFC的工程化应用提供理论参考。     

自支撑活化三维分级多孔碳阳极的制备及其在MFCs的应用

微生物燃料电池是一种可以从污水中直接回收能量的新型装置。然而,还有很多问题限制了它的广泛应用,其最大的困难在于输出功率密度低。阳极材料对于提高其功率密度和能量转换效率非常重要。本文基于生物质原料,利用化学试剂活化结合热处理,制备得到了一系列具有分级孔结构的自支撑活化三维碳基阳极。这种自支撑三维阳极具有优异的导电性、良好的电化学活性、出色的传质扩散以及优良的微生物相容性。其中,6mol/L KOH溶液处理得到的三维阳极具有最优的电化学活性和最佳功率输出,其最大功率密度高达121.45W/m³,是处理前的1.8倍。此研究为构筑高效功能三维碳基MFCs电极材料提供新思路和新方法。     

直接硼氢化物燃料电池阳极电催化剂研究进展

以硼氢化物作为燃料电池的燃料因其高的理论电动势和比能量而引起研究者的广泛关注。理论上,BH-4的电氧化反应为八电子反应,但实际上由于所用阳极电催化剂的不同,BH-4电氧化释放出的电子数也不同。如何抑制BH-4在阳极的水解反应,促进其八电子氧化反应一直是直接硼氢化物燃料电池研究中的核心问题。综述了近几年来国内外在直接硼氢化物燃料电池阳极电催化剂方面所取得的研究进展,并对这一领域中需要深入研究的主要问题进行了论述。     

碳纤维阳极构造对微生物燃料电池性能的影响

微生物燃料电池（MFCs）阳极性能受生物膜的影响,而生物膜则直接与阳极表面积有关。以不同长度和数量的碳纤维丝作为阳极,研究了阳极构造和表面积对MFC输出功率的影响。当阳极为单根长度为1 cm碳纤维丝时,MFC产生的最大功率密度最高,为10.50 W·m^-2,随着碳纤维丝长度逐渐增加（2～14 cm）,MFC产生的最大功率显著下降。以多根的长度为2 cm碳纤维丝构成阳极时,MFC的功率与根数（1～4 根）呈正比,当采用4根2 cm纤维丝时,MFC的最大功率密度为2.92 W·m^-2,该数值为单根8 cm碳纤维丝的2.78倍。观察碳纤维丝长度方向上的生物膜的分布表明：受碳纤维欧姆电阻的影响,在碳纤维丝电流引出端附近的生物量明显大于碳纤维其他地方,这说明：增加纤维丝长度虽可提高阳极的表面积,但并不能提高阳极的产电性能。     

Copper anode corrosion affects power generation in microbial fuel cells

Non‐corrosive, carbon‐based materials are usually used as anodes in microbial fuel cells (MFCs). In some cases, however, metals have been used that can corrode (e.g. copper) or that are corrosion resistant (e.g. stainless steel, SS). Corrosion could increase current through galvanic (abiotic) current production or by increasing exposed surface area, or decrease current due to generation of toxic products from corrosion. In order to directly examine the effects of using corrodible metal anodes, MFCs with Cu were compared with reactors using SS and carbon cloth anodes. MFCs with Cu anodes initially showed high current generation similar to abiotic controls, but subsequently they produced little power (2 mW m^‐2). Higher power was produced with microbes using SS (12 mW m^‐2) or carbon cloth (880 mW m^‐2) anodes, with no power generated by abiotic controls. These results demonstrate that copper is an unsuitable anode material, due to corrosion and likely copper toxicity to microorganisms. © 2013 Society of Chemical Industry     

原位双金属纳米颗粒YST复合阳极的构筑及其直接碳催化性能研究

研究了原位Cu析出和CuCo双金属析出的钇掺杂钛酸锶(YST)材料在作为直接碳燃料电池(DC-SOFCs)阳极时的结构及性能。首先采用燃烧法制备系列Co掺杂的Y_0.08Sr_0.92Ti_0.9-xCu_0.1Co_xO_3-δ(x=0,0.1,0.2,0.3)阳极材料。通过XRD、SEM、TEM等表征材料微观结构,结果表明Co掺杂量达到0.2时,氢气还原后的阳极材料析出均匀分布的CuCo双金属纳米颗粒。电导率测试表明CuCo双金属纳米颗粒有效提高了材料的电导率。CO氛围下的阻抗测试表明,析出CuCo双金属纳米颗粒的Co0.2阳极材料具有最小的极化阻抗,催化活性优于其他阳极材料,以其作为阳极的电池在800℃和碳为燃料时,最大功率密度可达591 mW·cm^-2,且具有良好的稳定性,是一种优异的DC-SOFC阳极材料。     

Microbial electrocatalysis with Geobacter sulfurreducens biofilm on stainless steel cathodes

Stainless steel and graphite electrodes were individually addressed and polarized at −0.60 V vs. Ag/AgCl in reactors filled with a growth medium that contained 25 mM fumarate as the electron acceptor and no electron donor, in order to force the microbial cells to use the electrode as electron source. When the reactor was inoculated with Geobacter sulfurreducens, the current increased and stabilized at average values around 0.75 A m⁻² for graphite and 20.5 A m⁻² for stainless steel. Cyclic voltammetry performed at the end of the experiment indicated that the reduction started at around −0.30 V vs. Ag/AgCl on stainless steel. Removing the biofilm formed on the electrode surface made the current totally disappear, confirming that the G.sulfurreducens biofilm was fully responsible for the electrocatalysis of fumarate reduction. Similar current densities were recorded when the electrodes were polarized after being kept in open circuit for several days. The reasons for the bacteria presence and survival on non-connected stainless steel coupons were discussed. Chronoamperometry experiments performed at different potential values suggested that the biofilm-driven catalysis was controlled by electrochemical kinetics. The high current density obtained, quite close to the redox potential of the fumarate/succinate couple, presents stainless steel as a remarkable material to support biocathodes.     

金黄色葡萄球菌生物膜形成及其与持留菌关系研究进展

金黄色葡萄球菌(Staphylococcus aureus)是目前临床上感染严重的致病细菌之一,随着抗生素的广泛使用,其耐药性及致病性问题日益突出,尤其形成生物膜及持留菌后,更为临床的治疗增加了难度.生物膜加强细菌耐药性,而持留菌是微生物种群中随机形成的细胞休眠体,对抗生素高度耐受.本文对金黄色葡萄球菌生物膜形成原因、...     

Modeling and Parameter Identification for a Biofilm in a Microbial Fuel Cell

A dynamic physical model of a microbial fuel cell (MFC) anode is presented and parameterized. It describes the evolution of current density and biofilm mass over time as a function of substrate concentration. The model is particularly useful for process monitoring or control purposes because it reproduces the dynamics of the MFC anode and contains comparatively few parameters. Parameters are identified using data from the response of the MFC to a substrate concentration pulse. Theoretical and practical identifiability of the parameters is evaluated, and parameter confidence intervals are determined.     

操作条件对固体氧化物燃料电池阳极反应转变的影响

研究了不同电流密度下,甲烷浓度、反应温度对甲烷在SOFC中反应由部分氧化到完全氧化转变的规律;测量了不同电流密度下,阳极出口气体产生速率;确定了甲烷浓度和电池反应温度变化时甲烷电化学反应由部分氧化转变为完全氧化的电流密度门槛值,及该门槛值与甲烷浓度、电池操作温度的变化关系.结果说明甲烷开始发生完全氧化的电流密度门槛值与甲烷浓度成正比;甲烷浓度一定,温度升高,甲烷开始发生完全氧化的电流密度的门槛值也随之提高.     

Monitoring of electro-active biofilm in soil

The present paper describes a new tool for on-line monitoring of biofilm growth in the soil. The work deals with the application in soil of the same electrochemical techniques already successfully used in water systems to monitor biofilm growth and mainly based on the cathodic polarisation of stainless steel electrodes. Experiments at laboratory level with sterilised and unsterilised soils, different soil humidities, different levels of nutrients have been performed by using a set of soil microcosms containing electrochemical probes. Weekly humidity tests and adjustments, chemical and microbiological analyses of the soils have been regularly carried out. Microbiological analyses and microscopy observation performed on the surface of the stainless steel electrochemical probes at the end of the tests confirmed a direct correlation between the increase of cathodic characteristic and the biofilm development on the working electrodes. The results suggest that simple electrochemical techniques are applicable in soil to monitor the early stage of biofilm growth on stainless steel. It was confirmed, in particular, a key role of soil humidity in the development of a stable and easily detectable biofilm. Soil humidity level resulted as the most critical and limiting factor for biofilm growth, more than the environment temperature, nutrient and carbon content. The best conditions to achieve a quick and full electro-active biofilm on electrodes in a soil microcosms suitable for experiments and studies at laboratory level have been detailed.     

Fabrication of continuous linear pores in an SOFC anode using unidirectional carbon fibers as sacrificial templates

We describe the manufacturing of a solid-oxide fuel cell anode of NiO−8 mol.% Y₂O₃-stabilized ZrO₂ with micro-scale continuous linear pores (CLPs) and nano-scale interparticle pore structures, achieved through thermal decomposition of unidirectional amorphous carbon fibers. The CLP structure prepared by this sacrificial templating method is characterized by its controllable uniform size, a tortuosity (ie, uniformity) of 1.003, and a coefficient of variation of 0.59. These highly regular CLPs are expected to minimize Knudsen diffusion, resulting in enhanced mass transport of hydrogen gas at the active sites, known as triple-phase boundary sites. Simulations using the Lattice Boltzmann Method (LBM) were used to determine the mass transport in the systems. An optimum diameter of 3 µm and an interparticle pore size of 185 nm was shown to maximize the acceleration of mass transport of H₂ and maintain the number of TPB sites to minimize concentration overpotential. Thus, the proposed porous design can increase the energy efficiency of a solid-oxide fuel cell primarily by reducing the concentration overpotential.     

Modeling the temperature field in the reforming anode of a button-shaped solid oxide fuel cell

A model predicting the temperature field in the porous reforming anode of a solid oxide fuel cell is presented herein. The model is based on mass, momentum, and heat balances of a chemically reacting mixture of gases within the porous matrix of the anode. The important novel characteristic of the model is the consideration of the both internal reforming and electrochemical reactions in the bulk of the porous anode. The electronic and ionic currents in the anodes are calculated utilizing the solution of the Poisson equations for the electric potentials in the porous medium. The transfer current density is described by the Butler–Volmer equation.The model is applied to investigate the temperature field and the reactive flow in button-shaped fuel cells with uniform and graded (multi-layer) anodes composed of Ni and YSZ particles with methane/water vapor mixture used as the fuel. The maximum temperature difference between the hot and cold spots of the anodes is found to reach up to 200 K. The results indicate that the generation of Joule heating caused by the current passing through the anode and the activation losses are the dominating heat sources compared to the gas-water shift and electrochemical reactions.     

Modeling of continuous-flow bioreactors with a biofilm with the use of orthogonal collocation on finite elements

The paper discusses mathematical modeling of two types of continuous bioreactors, a continuous stirred tank bioreactor (CSTBR) and a tubular bioreactor with biofilm on inner walls. The method of orthogonal collocation on finite elements (OCFE) was used for the modeling of a microbiological process occurring in the biofilm. Single-substrate Monod and Haldane kinetic models, and double-substrate Haldane–Monod kinetic model were used. The accuracy of the OCFE method was evaluated by comparison with the solution obtained using shooting method (SM). Profiles of substrate concentration, biofilm effectiveness factors, steady state-branches of CSTBR and distribution of substrate concentrations and biofilm thickness along the length of the tubular bioreactor were determined. Steady-state branches of the CSTBR were compared with experimental results from the literature. It was shown that the mathematical model gives good agreement. The efficiency of the OCFE method was demonstrated even for very steep gradients of concentrations in the biofilm.     

Power from marine sediment fuel cells: the influence of anode material

The effect of anode material on the performance of microbial fuel cells (MFC), which utilise oxidisable carbon compounds and other components present in sediments on ocean floors, estuaries and other similar environments is reported. The MFC anode materials were carbon sponge, carbon cloth, carbon fibre, and reticulated vitreous carbon (RVC). Power was produced through the microbial activity at the anode in conjunction with, principally, oxygen reduction at a graphite cloth cathode. After a period of stabilisation, open circuit voltages up to 700 mV were observed for most cells. Steady state polarisations gave maximum power densities of 55 mW m⁻² using carbon sponge as the anode; which was nearly twice that achieved with carbon cloth. The latter material typically gave power densities of around 20 mW m⁻². The performance of the cell was reduced by operation at a low temperature of 5 °C. Generally, for cells which were capable of generating power at current densities of 100 mA m⁻² and greater, mass transport was found to limit both the anode and the cathode performance, due primarily to the low concentrations of electro-active species present or generated in cells.     

Numerical analysis of thermal and electrochemical phenomena for anode supported microtubular SOFC

A 2D model considering momentum, heat/species transport and electrochemical phenomena, has been proposed for tubular solid oxide fuel cell. The model was validated using experimental polarization curves and the good agreement with the experimental data was attained. The temperature distributions show that temperature varies severely at the tube inlet than at the tube outlet. The heat generation and transfer mechanisms in electrodes, electrolyte and electrochemical reaction interface were investigated. The results show that the overall electrochemical reaction heat is produced at cathode/electrolyte interface, and a small portion of the heat is consumed at anode/electrolyte interface. The heat produced at cathode/electrolyte interface is about five times as much as that consumed at anode/electrolyte interface. Overwhelming part of the heat transfer between cell and outside occurs at cathode external surface. Most current flow goes into anode from a very small area where the current collectors locates. © 2009 American Institute of Chemical Engineers AIChE J, 2009