The anode chamber of each MFC had a 0.88mL capacity. A circular ion exchange mem- brane of 15mm diameter separated the anode and cathode. Three membrane types were in- vestigated (Table 1); CEM (Type 1), Nafion (Type 2), and IPMC made from Nafion 112 with gold electrodes fabricated using electroless plating using the method described in (Type 3). MFC anode and cathode electrodes were made from carbon fibre veil, with surface areas of 1800mm 2 and 4500mm 2 , respectively (Figures 2(a) and 2(b)). The open to air cathode of each system was coated with a conductive latex made using a method derived from , to maintain a continuous redox reaction without the need to hydrate the cathode electrode. The performance of IPMC surface electrodes to function as the MFC anode and cathode, with the polymer layer used as the ion exchange membrane, was investigated in an additional configuration without carbon veil and conductive rubber MFC electrodes (Type 4).
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Figure 22: Synthesis route of the N-doped WC nanoarrays (a), i-V curves of water splitting with the N-WC as anode and cathode electrodes compared with N-WC as the cathode and Ir/C as the anode (b), and video snapshot of the water electrolysis with a 1.5 V commercial battery (c). Reprinted with permission from . Copyright 2018 Nature Publishing Group.
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The batch electrochemical reactor is a 360 ml glass vessel (10×6×6 cm) Figure 1c. Various materials of aluminium (Al), copper (Cu), iron (Fe), steel (As), and zinc (Zn) are used as anode and cathode electrodes. The area of each electrode is 36 cm 2 (9×4×0.1 cm). The distance between electrodes is adjusted to 2 cm. The AC electrical source has maximum electrical power of 60 W. To evaluate the effect of electrolysis, on the sulfate removal process, samples undergo with different current density (1-8 mA/cm 2 ), electrodes material (Al, Cu, Fe, As, and Zn), pH (ca. 6-8), and different times (5-40min). Magnetic stirrer (AiKa, Germany) is used for homogeneous mixing of water samples (Table 2). For each test, 200 mL of sample water is poured into the reactor. All tests are performed at laboratory temperature (20 ˚C). Chloride acid and sodium hydroxide solutions (0.1 N) are used for pH adjustment.
microorganisms and prokaryotic microorganisms, which also include bacteria and archaea [15, 16]. At present, most of the reported exoelectrogens are bacteria, which are distributed in Proteobacteria, Firmicutes, Acidobacteria and Actinobacteria , the Shewanella studied in this paper belong to gammaproteobacteria. Moreover, non-exoelectrogens also play an indispensable role in an electrochemical system. In 1911, Potter first discovered that Escherichia coli could produce a voltage of 0.3-0.4 V by oxidizing substrates with chemical electronic mediators . In 1931, Cohen obtained a voltage of 0.5 V by using a mixed bacteria system . Non-exoelectrogens also significantly affect the performance of bioelectrochemical systems. In a BES, electrogenic bacteria oxidize organic matter and provide electrons to the anode , while different electron acceptors can reduce biologically or abiotically at the cathode according to the function of the system [21, 22]. Exoelectrogens play an important role in BES, and the substrates and inoculum sources affect the types of exoelectrogens and the performance of the BES. The function of the non-exoelectrogens is to compete with the exoelectrogens, which affects the electrolytic performance of the exoelectrogens. Therefore, the activity and electrochemical characteristics of the exoelectrogens and non-exoelectrogens are very important to the operational performance of a BES.
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Space charge measurements were made using a pulsed electro-acoustic (PEA) system. A voltage of 3 kV was applied to disks approximately 0.75 mm thick (i.e. an average field of 4 kV.mm -1 ) for 10,800 s (3 hours) at room temperature (293 ± 3 K). The sample was then short-circuited for at least 3600 s (1 hour). The space charge was measured periodically during the charging and discharging periods. We report selected representa- tive results here for 10% w/w filled samples showing the charge accumulation at 3 hours and the subsequent decay. As the charge accumulates, the electric field is distorted and so we also report the observed electrical field after the 3-hour charging period. In each graph, the vertical dotted lines indicate the cathode (left) and an- ode (right), the grey line indicates the charge distribu- tion at the end of the charging period (i.e. before short circuiting) and arrows show the charge decay with time.
To prevent any increase in pH due to the hydrogen evolution reaction, the pH was readjusted to 7 by adding dilute HCl or NaOH solutions during the experiments. The influence of cathode materials on the cell performance is depicted in Fig. 2. Fig. 2(a) shows the percentage of gold recovery vs. time from 500 mg L -1 of Au(III) solution by using different cathode types within 3 h of experiment. It is observed that, RVC can recover gold faster than the other types of cathodes in this study. In order to compare the cathode performance, the percent of recovery after 90 min using different cathodes is presented in Table 2.
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velocity plots. This is primarily due to the interaction of the tracked bubble with other bubbles that results in dynamic coalescence. Nevertheless, the straight-line plot that is superimposed on the velocity plots clearly demonstrates the trend of the velocity data in each case. It can be seen that the velocity of the experiments with the external magnetic field induces greater velocity, independent of the anode inclination. The Figure 4 also shows a complex velocity pattern due to coalescence process arising from bubble-bubble interaction. However, it is to be noted that due to the large number bubble nucleation on the anode surface at any instant of time makes it difficult to observe the growth of any particular bubble.
Figure 4. (a) The 1 st and (b) 10 th constant discharge/charge profiles of the MS and N-MS electrode. Figure 5a compares the cycle performance of MS and N-MS composites. The specific capacity of the N-MS composites can remain at 738 mAh g -1 at the current density of 0.5 C after 100 electrochemical cycles. However, the specific capacity of the pure MS anode electrode is 629 mAh g -1 . This is because the pure MS anode electrodes suffer from poor electronic conductivity during the electrochemical cycles. Besides, the structure of the pure MS anode electrodes may be damaged by the high current density [22, 23]. For the N-MS anode, the proicess of the N-doping can effectively enhance the conductivity and inhibit the volume change.
quite sustainable and cost effective solution to the challenges associated with the use of fuel cells in renewable power grids. The development of an anode electrode for the BioGenerator was subject of this work. The unique features of the BioGenerator require unique electrodes, and more specifically anode. The combination of biological cathodic liquid and the hydrogen gas fuel require specific hydrophobic/hydrophilic properties of the anode. Several different methods for anode formation were studied. The spreading technique was found to be most appropriate for the conditions in the BioGnerator. It was employed to fabricate three-layer hydrophobic PTFE- bound anode electrodes. The reproducibility, durability and performance stability of the mentioned electrodes were studied using i-V curves, ex-situ cyclic voltammetry, and through- plane gas permeability. In addition, the effect of hydrophobic polymer content (PTFE) in the backing substrates, including woven-fiber carbon cloth and nonwoven-fiber carbon papers, on the gas permeability, hydrophobicity, and long-term durability of anode electrodes was studied. Results showed that woven-fiber carbon cloth impregnated with 80-100 wt.% PTFE gives an enhanced durability towards flooding in the course of continuous operation at 100 mA cm -2 . Moreover, causes of failure in the performance of the anode electrodes were assessed and results showed that the mass transfer is the main source of limitation in the long-term operation.
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The influence of the cathode travelling frequency on the side gap is illustrated in Figure 7 for the micro slits that were obtained at an anode vibration amplitude of 5 µm, an anode vibration frequency of 100 Hz, a cathode travelling amplitude of 70 µm, a pulse period of 6 µs, a voltage of 6 V, and a pulse duration of 30 ns. Figure 7(a) indicates that the average side gap increases gradually with the cathode travelling frequency, which ranges from 1 to 2 Hz; then, the side gap slightly changes with a further increase in cathode travelling frequency from 2 to 5 Hz. The minimum deviation range of the side gap occurs at the cathode travelling frequency of 2 Hz. The micro slit that was prepared at the cathode travelling frequency of 2 Hz has the best homogeneity among the five micro slits, as shown in Figure 7(b). Therefore, a frequency of 2 Hz and an amplitude of 70 µm are optimal for cathode travelling.
Conduction is initiated by free electrons which accelerate in the field until they begin to make inelastic collisions with gas molecules. The major products resulting from these collisions are electrons, ions and photons. The ions and electrons move under the influence of the field but in opposite directions. The electrons travel to the anode and make further inelastic collisions with gas molecules on the way. The ions are drawn to the cathode and collect electrons from its surface to become neutral particles again. Ions bombarding the cathode also cause extra electrons to be emitted, and thus a cycle is established which allows the current flow to be sustained. The discharge current grows until it is limited by the external circuit, usually in tens of nanoseconds. The electric field between the electrodes is now distorted by the presence of charges and the distinctive dark and bright regions of the discharge are developed. Photons are emitted from the bright regions, where excitation occurs, giving the discharge its characteristic appearance. The photons play an important role in the maintenance of the discharge, as some produce electrons from the electrodes, while others produce electrons in the gas. In the steady state, every electron leaving the cathode creates enough ionisation and excitation in the gas to cause, ultimately, one further electron to be emitted from the cathode. This is known as the maintenance condition. The operating conditions in the steady state are determined by the parameters of the circuit in which the glow discharge is connected.
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However, analyzing the initial corrosion period and latter corrosion period together may have the possibility to lose some significant information, so the separated 2 periods are illustrated in Fig. 9 (1-4 cycle) and Fig. 9 (5-8 cycle). In the initial corrosion period, the cathode polarization slope of each case is -59.97, -59.20 and - 86.35mV/dec respectively and anode polarization slope is 408.64, 166.17 and 39.80mV/dec. In later corrosion period, the cathode polarization slope of each case is -145.80, - 117.36 and -121.87mV/dec respectively and anode polarization slope is 98.11, 63.45 and 22.43mV/dec. By comparing with the 2 periods, with the increasing of corrosion time, the cathode polarization slope has a slightly easing up and the anode polarization slope has a slightly easing down especially in case 1 which drops from 408.64 to 98.11mV/dec. What should be noticed is that in later corrosion period all the absolute value of anode polarization slope is lower than initial corrosion period. This means increasing of chloride contents in anode and corrosion time can both reduce the reaction resistance in anode. Moreover, although cathode polarization slope remains fluctuating, the cathode polarization slope in the later corrosion period is higher than initial corrosion period in all cases.
A single-chamber, air-cathode MFC was constructed (Figure 1) with a reactor, resistance box and data processing module. External resistance was fixed at 1000 Ω except as indicated. The anode area was 113 cm 2 . The upper part of the reactor consisted of a circular vessel, which was made of polymethyl methacrylate with a diameter of 120 mm with a height of 120 mm. A 120 mm diameter piece of carbon mesh was placed in the bottom of the vessel to act as the anode. The design of system allows the aeration in the upper of compost and anaerobic condition in the bottom near anode, which is necessary for electricity generation. Two layers of glass fiber with a diameter of 130 mm were inserted below the carbon mesh. Because of its open structure and weave, the carbon mesh minimized biofouling . To realize full contact with the reactor vessel and to prevent short circuit during
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It was previously shown that the increase in cathode area affected positively on the performance output of the MFCs (Cheng and Logan, 2011; Kim et al., 2015). In the present study, we investigate a supercapacitive MFC (SC-MFC) system and the effect of relative anode and cathode size on the overall perfor- mance of the system. We use the experimental data from these experiments to construct a simple predictive linear model for a hypothetical SC-MFC with a cylindrical design in order to forecast performance of a larger scale device. We demonstrate that the per- formance of a SC-MFC based on conventional materials can be improved to levels suitable for powering practical electronic devices by optimizing design parameters.
45.1% by Eq. (3) and voltage stable was 7v at the process of electrolysis. The energy consumption was 7.1 kilowatt hour for removing 1kg NaCl by Eq. (4). According to the calculation results, current efficiency was low while energy consumption was high, the reason may be that anode use low concentration of HCl solution whose conductivity was low and leading to higher voltage , so that the energy consumption was higher.
The cell used in this experiment has an active area of 50 cm 2 . It used printed circuit board to substitute both anode plate and cathode plate. The printed circuit board with triple serpentine flow fields has 49 segments. The hydrogen flows into the segment A01 and flows out of G07 while the air flows into the segment A07 and flows out of G01(Fig.1). The membrane electrode assembly (MEA) used in this experiment was bought from Wuhan Xinyuan Corporation which was similar with the published paper[13-15]. Anodic and catholic catalyst with 0.4 mg/cm 2 Pt were coated on the membrane and the
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4.3. Formation of Internal DC Electric Circuit in Coil-EEFL Lamp For the optimization of the coil-EEFL lamps, we have studied the details of the lighting mechanisms of the coil-EEFL lamps. Figure 6 schematically illustrates the lighting mechanisms of the coil-EEFL lamp. The glass tube is a good electric insulator, so that the electrons from the metal electrodes on the outer glass wall cannot penetrate through the glass wall. Consequently, the external driving cir- cuit does not provide the electrons to the Ar gas space. Only electric field from the electrodes vertically penetrates through the thickness of the glass wall and reaches to the phosphor screen. So far as the phosphor screen is made with a few layers of the phosphor particles, the phosphor particles under the electrodes are polarized with the vertical electric field from the metal electrodes. If the phos- phor screens are made with the layers thicker than 5 layers of the particles, the light output from the coil-EEFL lamps goes down with the numbers of the phosphor particles in the screen.
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Title The Development of Nanomaterials for High Performance Lithium Ion Battery Anodes Many industries spanning macro to micro applications need advanced energy storage capabilities and Li + batteries are the prevalent technology to meet those demands. High Li + capacity semiconductor materials (e.g. Si, Ge) in concert with carbon nanotubes (CNTs) have been investigated as alternative materials for Li + batteries. Nanomaterials offer many advantages to high performance batteries by increasing storage capacities, Li + diffusion, and more adequately accommodating volumetric expansion that occurs in cycling. Silicon and Ge are known to have very high Li + storage capacities of 4200 and 1600 mAh/g, respectively, and can be used in combination with CNTs to form free-standing anodes. The proper incorporation of semiconductor materials onto and throughout a CNT network through thin film, solution processing, and gas-phase processing techniques, has been studied to develop ultra-high capacity free- standing electrodes. Given the free-standing nature, the removal of binders and metal foil current collectors contributes to an increased electrode energy density over conventional composites on metal substrates. The CNT and semiconductor materials have been characterized in coin and pouch cells upon identifying the synthesis parameters and processing steps to be optimized for several of the incorporation techniques. Anodes fabricated through PVD techniques realize capacities over 800 mAh/g and a predicted >50% increase in energy density over conventional graphite anodes. The use of thin film Ti contacts on high energy Ge-SWCNT anodes demonstrates a 5-fold improvement in Li + capacity at 1C extraction rates, a drastic improvement in the anode power capabilities. Pairing these electrodes with a high power cathode LiFePO 4 can lead to a 60% improvement in power and energy density. A 3-
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Energy storage demands for next generation electric vehicles and grid storage have increased significantly during the last decade, with lithium ion technology remaining the most likely contender to meet these requirements in the short to medium term. The key requirements for vehicle energy storage are high gravimetric and volumetric energy density, whereas for grid storage, cycle life is the most important parameter. To obtain high energy density batteries, silicon anode materials with a theoretical capacity of 3579 mAh g −1 have been a major focus of recent
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Though we have concentrated on water effects in this paper there are several other aspects to the model that can be exploited. For example, a parametric study with respect to the microstruc- tural properties of the CCL and conditions under which proton migration is limiting. Our purpose has been to demonstrate the ability of the model to capture complex phenomena. There are several extensions to the model that we are currently pursuing. In order to study effects such as hydrogen and oxygen (as well as water) crossover, the anode catalyst and gas-diffusion layers must be included. In addition, extension to two dimensions will provide details of the non-uniformities down the channels.
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