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Electricity access is an essential factor for any nation’s fast-growing economic and technological development. Therefore, to meet the fast-growing world population, the adoption of a mix of energy sources, including renewable energy, is one of the ways to address the paucity supply of energy worldwide. In this paper, the performance yields of five solar photovoltaic (PV) modules, named PV1, PV2, PV3, PV4, and PV5, from different manufacturers were analyzed and compared to their respective cost benefits for profitable customer’s choice. The study on the panels was conducted at the geographical locations of 25.7535° S latitude and 28.2079° E longitude, with an average perimeter of 525.6 m in Pretoria, South Africa. The panels were installed without shading under the same condition of solar irradiation. The power output of each module was collected three times a day for six months. The analysis showed that the power outputs or performances of the respective modules are majorly affected by their surface temperatures as indicated by the values of multiple regression correlation of 92.9%, 96.9%, 99.1%, 97.2%, and 77.5% between the respective modules’ power outputs and temperature. The study also showed a techno-economic evaluation method that helps to economically alleviate the cost of solar PVs and balance the choice of the PV panels according to their short-term performances.

Developing low-cost and high-performance anodes is of great significance for wider applications of microbial fuel cells (MFCs). In this study, microalgae and pyrite were co-pyrolyzed (P/MC) and then coated on carbon felt (CF) with PTFE as a binder. P/MC modification resulted in increased electroactive surface area, superhydrophilicity and higher biocompatibility. Besides, the P/MC-CF anode reduced the charge transfer resistance from 35.1 Ω to 11.4 Ω. The highest output voltage and the maximum power density of the MFC equipped with the P/MC-CF anode were 657 mV and 1266.7 mW/m2, respectively, which were much larger than that of the MFC with the CF anode (530 mV, 556.7 mW/m2). The P/MC-CF anode also displayed higher columbic efficiency (39.41%) than the CF anode (32.37%). This work suggests that pyrolyzing microalgae with pyrite is a promising method to enhance the performance of MFCs.

The harmless reaction process makes the fuel cells possess the environment-friendly characteristic, but the application of fuel cells is limited by their low fuel utilization. To improve this, a model of vapor-feed microfluidic fuel cell with a novel geometric configuration is established in present study, and the effects of various parameters on cell performance are investigated in detail. Simulation results show that structural parameters contribute significantly to the improvement in cell performance. After a series of optimizations, the maximum power density of 47.43 mW/cm2 is achieved, the fuel utilization and exergy efficiency are increased to 46.03% and 5.24%, respectively. This indicates that the structural optimization measures such as tower-type gas chamber and embedded electrode are significant for improving the performance of the vapor-feed microfluidic fuel cell.

In the present study, we present a 3D oriented CuS/Cu2O/Cu nanowire photocathode grown on copper foam. This newly developed photocathode can effectively enhance the separation of electron–hole pairs and anti-photocorrosion as a result of the nanowire structure and bandgap gradient. In the meantime, it can provide more active sites and promote light utilization due to the vigorous porous structure and proper pore size. Experimental results confirmed the improved photoelectrochemical activity of the proposed photocathode as compared to the planar photocathode with CuS/Cu2O/Cu nanowires. The in-cell performance measurements of a dual-photoelectrode photocatalytic fuel cell with the proposed photocathode also demonstrated the enhancement of the cell performance by the proposed photocathode, presenting about 88% improvement in the maximum power density. The 3D oriented CuS/Cu2O/Cu nanowire photocathode represents a new route for the development of high-performance photocathodes, which can also be applied in other photoelectrochemical systems.

To directly use a CO2–CH4 gas mixture for power and CO co-production by proton-conducting solid oxide fuel cells (H-SOFCs), a layer of in situ reduced La0.6Sr0.2Cr0.85Ni0.15O3−δ (LSCrN@Ni) is fabricated on a Ni–BaZr0.1Ce0.7Y0.1Yb0.1O3−δ (BZCYYb) anode-supported H-SOFC (H-DASC) for on-cell CO2 dry reforming of CH4 (DRC). For demonstrating the effectiveness of LSCrN@Ni, a cell without adding the LSCrN@Ni catalyst (H-CASC) is also studied comparatively. Fueled with H2, both H-CASC and H-DASC show similar stable performance with a maximum power density ranging from 0.360 to 0.816 W cm−2 at temperatures between 550 and 700 °C. When CO2–CH4 is used as the fuel, the performance and stability of H-CASC decreases considerably with a maximum power density of 0.287 W cm−2 at 700 °C and a sharp drop in cell voltage from the initial 0.49 to 0.10 V within 20 h at 0.6 A cm−2. In contrast, H-DASC demonstrates a maximum power density of 0.605 W cm−2 and a stable cell voltage above 0.65 V for 65 h. This is attributed to highly efficient on-cell DRC by LSCrN@Ni.

Air-breathing high-temperature proton exchange membrane fuel cell (HT-PEMFC) gets rid of the cumbersome air supplying systems and avoids the water flooding problem by directly exposing the cathode to air and operating the fuel cell at elevated temperature. Performance of the air-breathing HT-PEMFC is dependent on many factors particularly the cathode flow field configurations. However, studies about air-breathing HT-PEMFCs are quite limited in the literature. In the present study, an experimental testing system was setup for the performance measurement of the air-breathing HT-PEMFC. A 3D numerical model was established and validated by the experimental data. Effects of the cathode flow field configurations including the opening shape, end plate thickness, open ratio and opening direction on performance of the air-breathing HT-PEMFC were experimentally and numerically investigated. It was found that the cathode end plate thickness and upward or sideways orientation have the least effect on the performance. The maximum power density of 160 mW/cm2 at the current density of 394 mA/cm2 can be achieved for the cathode flow field with slot holes and an open ratio of 75%.

Triboelectric nanogenerators (TENGs) are a well-known energy supply technology. Their output performance is highly important given their intended use in real-world applications. Expanded polytetrafluoroethylene (ePTFE) membranes, which are lightweight, fibrillated, microporous membranes formed by the expansion and stretching of PTFE, possess excellent flexibility and elasticity, unlike the traditional PTFE films that they are made from. Therefore, ePTFE membranes have tremendous potential to be a triboelectric material for energy harvesting. As the most important parameter in ePTFE processing, the uniaxial expansion ratio determines the final morphology of the ePTFE and, thus, the output performance of TENGs. Hence, it requires systematic study. Here, folded-paper TENGs consisting of ePTFE membranes with different expansion ratios and nylon fabrics as two paired tribolayers (i.e., ePTFE/Nylon-TENGs) were fabricated. A systematic study concerning the effect of the expansion ratio on the output performance of the ePTFE/Nylon-TENGs was carried out. The output performance of the ePTFE/Nylon TENGs with expansion ratios ranging from 0 to 400% were measured and compared. The results showed that the output electrical signals of the ePTFE/Nylon-TENGs first increased with the expansion ratio and then decreased steadily, with an optimum performance at an expansion ratio of 100%. In addition, the output performance of the TENGs with solid PTFE was approximately the same as that of the ePTFE/Nylon-TENGs with an expansion ratio of 300%. The ePTFE/Nylon-TENGs had excellent and stable performances and yielded a maximum power density of 1.01 mW/cm2, with an effective area of 1 cm2 and a load resistance of 1 MΩ. This work suggests that ePTFE is an effective material for improving the output performance of ePTFE-based TENGs.

The concept of a self-powered water desalination device with the capability of simultaneous electricity generation is introduced. The as-fabricated metal-air desalination battery takes the advantage of integration of ion selective membranes with an aluminum-air battery in a three-chamber cell. The maximum power density of 2.83 W m−2 at 6.58 A.m−2 current density and 0.43 V output voltage is obtained using natural saltwater as the electrolyte. The as-fabricated device decreases the salinity of Caspian saltwater by 37.8% with 10 mW h energy generation in 14-h operation. The obtained results are promising to present considerable room for improvement of the as-fabricated device.

In this paper, the electrochemical performance of nanostructured LaNi0.6Fe0.4O3-δ (LNF) infiltrated La2NiO4+δ (LNO) material was evaluated as a potential cathode for BaZr0.1Ce0.7Y0.2O3-δ (BZCY)-based proton-conducting solid oxide fuel cell (H-SOFC). The performance of LNO backbone cathodes with different loading amounts of LNF infiltrated phase were investigated, and electrochemical studies implied that the single cell with about 31 wt% LNF infiltrated cathode exhibited the lowest polarization resistance of 0.027 Ω cm2 and the highest maximum power density of 969 mWcm−2 at 700 °C, which were encouraging compared with that in previous reports of cobalt-free cathodes for H-SOFCs. This work demonstrated that the infiltrated LNF-LNO cathode had a great potential for H-SOFC and the optimization of the loading amount of LNF nanoparticles on LNO was critical for the fuel cell performance.

Different types of self-supported SOFCs (i.e., anode-supported, cathode-supported and electrolyte-supported SOFCs) have been compared in literature mostly from technical point of view. In this study, the mentioned types of SOFCs are compared from technical and economic points of view simultaneously. In this regard, “maximum power density” and “material cost of PEN layer” are taken as objective functions. These functions are evaluated through numerical modeling and based on available cost data, respectively. The results illustrate that the cathode-supported SOFC is the optimal choice when power density is regarded alone. On the other hand, the electrolyte-supported SOFC is observed to be the optimal option when the material cost of PEN is considered as the only objective function. However, the anode-supported SOFC makes the best trade-off between the two objective functions when they are simultaneously taken into consideration. The results also indicate that the electrolyte-supported SOFC leads to a symmetrical and most uniform current density distribution as compared to the electrode-supported ones in which peak local current densities tend toward non-supporting side. The paper discusses in detail the reasoning for the mentioned observations.

Sludge microbial fuel cell (SMFC) is capable of extracting biomass energy directly from the sludge while generating electricity. However, most of organic matters in the excess sludge are the cell substances that are difficult to be used by microorganism directly. In this paper, adding graphene oxide (GO) and reduced graphene oxide (rGO) in SMFC was proposed and their advantages were reflected by no requiring external energy, in-situ promoting the electricity production and reducing sludge effectively. The results showed that the contents of lactate dehydrogenase (LDH) for adding 0.4 g GO in SMFC (0.4-GO SMFC) and adding 0.4 g rGO in SMFC (0.4-rGO SMFC) were 2 and 1.81 times higher than that of adding nothing in SMFC (ordinary SMFC), respectively. The species and compositions of organic matter in 0.4-GO SMFC and 0.4-rGO SMFC decreased significantly and their sludge reduction rate were 3 and 2.2 times that of ordinary SMFC, respectively. Comparing with ordinary SMFC, the maximum power density of 0.4-GO SMFC and 0.4-rGO SMFC was up to 214.09 and 80.52 mW m−3 separately, and their internal resistance decreased by 71% and 48%, respectively. Thus, it can be concluded that GO and rGO had the function of breaking cell and accelerated electrons transporting, so they could greatly promote the sludge reduction and electricity production of SMFC.

In this study, producing biosurfactant from used vegetable oil in the anode chamber of a microbial electrosynthesizing fuel cell (MEFC) with electrical energy production was investigated. Up to 10 mL/L used vegetable oil was used with an acclimated bacterial culture—Serratia sp. in the anode chamber. The biosurfactant production and bacterial growth in the anode chamber was compared to a continuously stirred batch reactor of comparable size. Up to 3.05 g/L of biosurfactant was produced in the anode solution and a reduction of surface tension to 25.2 mN/m was reached after 7 days of the MEFC operation. At the same time, a maximum power density of 1.13 mW/m2 was produced. The MEFC was further characterized using the electrochemical impedance spectroscopy. Mathematical expression was established to model the total impedance of the MEFC. The production of the biosurfactant from the used vegetable oil waste in the anode chamber and also producing electric power makes the MEFC multifunctional.

Energy storage is increasingly demanded in many new niches of applications from wearables to unmanned autonomous vehicles. However, current energy storage systems are unable to fulfill the power requirements (high energy at high power) needed for these novel applications. Recently, Li-ion capacitors (LICs) have been spotted as hybrid devices with the potential to display high energy and high power. Nevertheless, it is still a great challenge to achieve high performance LICs due to the unmatched kinetic properties and capacity between anode and cathode materials. Herein, we are presenting our first seminal report on the use of BiVO4 nanorods as a new anode material for LICs coupled with a partially reduced graphene oxide (PRGO) cathode. The BiVO4 nanorods show an excellent reversible capacity of 877 mA h g−1 (ultrahigh volumetric capacity of 4560 mA h cm−3) at 1.1 A g−1 with a great capacity retention (in half-cell design), which is the highest value reported so far for metal vanadates. Later on, a LIC was constructed with BiVO4 as the anode and PRGO as the cathode electrode, delivering a high energy density of 152 W h kg−1 and a maximum power density of 9.6 kW kg−1 compared to that for hard carbon and intercalation (such as Li4Ti5O12 and Li3VO4) based anode materials. Additionally, the BiVO4//PRGO LIC exhibits a good cyclability of 81% over 6000 cycles. Thus, this investigation opens up new opportunities to develop different LIC systems., DPD acknowledges the support of University of Adelaide, Australia for the grant of Research Fellowship (Research for Impact). Funding from MINECO (MAT2015-68394-R) is acknowledged. The ICN2 is supported by the Severo Ochoa programme of the Spanish Ministry of Economy, Industry and Competitiveness (MINECO, grant no. SEV-2013-0295) and funded by the CERCA programme/Generalitat de Catalunya. K. J. R. is grateful to the Alexander von Humboldt (AvH) foundation for a post-doctoral fellowship. The authors also gratefully acknowledge support by the Catalysis Research Centre at TU Munich and the support from the Ministry of Education, Youth and Sports of the Czech Republic (LO1305) and the assistance provided by the Research Infrastructure NanoEnviCz, supported by the Ministry of Education, Youth and Sports of the Czech Republic under project no. LM2015073. The authors gratefully acknowledge the support by the Operational Programme Research, Development and Education – European Regional Development Fund, project no. CZ.02.1.01/0.0/0.0/15_003/0000416 and the project CZ.02.1.01/0.0/0.0/16_019/0000754.

In this study, a bio-photoelectrochemical system (BPES) is constructed by coupling a reduced graphene oxide/TiO2/Ag (RGO/TiO2/Ag) photocathode with a bioanode. The BPES integrated advantages of both photocatalyis process and bioelectrochemial system, and high efficiency of tetracycline (TC) degradation and simultaneous electricity generation were achieved. Under the conditions of 10 mg L−1 TC and 200 Ω external resistance, 95.21% of TC in wastewater can be removed within 8 h. The BPES with the RGO/TiO2/Ag photocathode shows higher columbic efficiency (CE) and mineralized current efficiency (MCE) than the system with a pristine TiO2, RGO/TiO2 or TiO2/Ag photocathode. The maximum power density is 133 mW m−2 under light illumination and 101 mW m−2 in the dark. The radical trapping experiments and fluorescence spectra analysis indicate superoxy group (·O2−) is the primary active oxidant. In addition, the underlying mechanism for the boosted TC degradation in the BPES are proposed. Our results suggest that BPES can be served as an efficient approach for the remediation of antibiotic-contaminated wastewater.

Thermophilic microbial fuel cell (TMFC) offers many benefits, but the investigations on the diversity of exoelectrogenic bacteria are scarce. In this study, a two-chamber TMFC was constructed using ethanol as an electron donor, and the microbial dynamics were analyzed by high-throughput sequencing and 16S rRNA clone-library sequencing. The open-circuit potential of TMFC was approximately 650 mV, while the maximum voltage was around 550 mV. The maximum power density was 437 mW/m2, and the columbic efficiency in this work was 20.5 ± 6.0%. The Firmicutes bacteria, related to the uncultured bacterium clone A55_D21_H_B_C01 with a similarity of 99%, accounted for 90.9% of all bacteria in the TMFC biofilm. This unknown bacterium has the potential to become a new thermophilic exoelectrogenic bacterium that is yet to be cultured. The development of TMFC-involved biotechnologies will be beneficial for the production of valuable chemicals and generation of energy in the future.

Anolyte acidification is an inevitable restriction for the bioelectricity generation of buffer-free microbial fuel cells (MFCs). In this work, acidification of the buffer-free KCl anolyte has been thoroughly eliminated through anolyte recycling. The accumulated HCO3- concentration in the recycled KCl anolyte was above 50mM, which played as natural buffer and elevated the anolyte pH to above 8. The maximum power density (Pmax) increased from 322.9mWm-2 to 527.2mWm-2, which is comparable with the phosphate buffered MFC. Besides Geobacter genus, the gradually increased anolyte pH and conductivity induced the growing of electrochemically active Geoalkalibacter genus, in the anode biofilm. Anolyte recycling is a feasible strategy to strengthen the self-buffering capacity of buffer-free MFCs, thoroughly eliminate the anolyte acidification and prominently enhance the electric power.

Microbial fuel cells (MFCs) represent a promising approach for remediation of toxic vanadium (V) contaminated environment. Herein, enhanced V(V) reduction and bioelectricity generation are realized in MFCs with biocathode. Synergistically electrochemical and microbial reductions result in the nearly complete removals of V(V) within 7 d operation with initial concentration of 200 mg L −1 . Maximum power density of 529 ± 12 mW m −2 is obtained. Electrochemical tests reveal that biocathode promotes electron transfers and reduces charge transfer resistance. XPS analysis confirms that V(IV) is the main reduction product, which precipitates naturally under neutral conditions. High-throughput 16S rRNA gene sequencing analysis indicates that the newly appeared Dysgonomonas is responsible for V(V) reduction and Klebsiella contributes mainly to bioelectricity generation in MFCs with biocathode. This study further improves the performance of remediating V(V) contaminated environment based on MFC technology.

To enhance azo dye reduction in cathode of microbial fuel cells (MFCs) and power generation, a novel cathode modification method was developed on carbon paper (CP) through immobilization of redox mediators (RMs) with self-assembled peptide nanotubes (PNTs) as the carrier. Results showed that the optimum peptide concentration for PNT self-assembly on electrode and Orange II decolorization in MFCs was 2 mg mL −1 . The PNT/RMs/CP electrodes exhibited higher electrocatalytic activities than PNT or RM solely modified electrodes and raw carbon paper electrode. MFCs loaded with the riboflavin (RF)/PNT modified cathode (PNT/RF/CP) or anthraquinone-2, 6-disulfonate (AQDS)/PNT modified cathode (PNT/AQDS/CP) showed an enhanced decolorization rate to Orange II compared to that with the control electrode, with the reduction kinetic constants increased by 1.3 and 1.2 folds, respectively. Furthermore, the MFCs with the PNT/AQDS/CP cathode and PNT/RF/CP cathode generated a higher maximum power density of 55.5 mW m −2 and 72.6 mW m −2 , respectively, compared to the control (15.5 mW m −2 ). The PNT/RMs modification could reduce cathode total internal resistance and accelerate electron transfer from electrodes to dyes, which may result in the enhanced performance of MFCs.

The effect of anodic pH on Microbial fuel cells (MFCs) inoculated with marine consortia was investigated to characterize the microbial community adaptation to possible pH environmental changes and to define the pH extreme boundaries beyond which MFCs do not run properly. Tests were conducted in triplicate using different feeding pH values (pH feed ) ranging from 3 to 13. The MFCs inoculated with marine consortia had a strong self-regulation ability and actively counterbalanced small variations in pH feed maintaining the pH inside the anodic chamber (pH anode ) close to neutrality. As soon as the pH anode deviated from neutrality it affected MFCs' performances. Alkaline conditions with pH anode values between 8 and 10 corresponded to the formation of a denser biofilm together with the best performance in terms of maximum power density (P max ). Conversely, when the pH anode reached values lower than 5.5 or higher than 10, a sharp drop in MFC performances, as well as a decrease of viable population, were observed. Interestingly, the system was able to survive these extreme conditions and restart working effectively when neutrality was reset. The obtained results underline the high adaptability and recovery ability of anodic marine consortia even in extreme conditions, suggesting the employment of this inoculum for MFC applications as biosensors for on-site seawater monitoring or as power supply units to be installed in remote area.

A bioanode was constructed using glucose oxidase enzyme (GOx) supported on multiwalled - carbon nanotubes (MWCNTs) in the presence of glutaraldehyde (GA) (GOx/MWCNTs-GA) and evaluated in an air-breathing hybrid glucose microfluidic fuel cell (HG-μFC). The air-breathing HG-μFC operated under physiological conditions (5 mM glucose at pH 7 with an air-exposed cathode) delivers an open circuit value of 0.72 V with 610 μW cm −2 of maximum power density, and shows potential possibilities to develop future implantable applications.

This work presents the characterization of a self-powered glucose biosensor using individual sequential assays of human plasma glucose obtained from diabetic patients. The self-powered glucose biosensor is exploited to optimize the assay parameters for sensing plasma glucose levels. In particular, the biofuel cell component of the system at pH 7.4, 37 °C generates a power density directly proportional to plasma glucose and exhibited a maximum power density of 0.462 mW·cm−2 at a cell voltage of 0.213 V in 5 mM plasma glucose. Plasma glucose is further sensed by monitoring the charge/discharge frequency (Hz) of the integrated capacitor functioning as the transducer. With this method, the plasma glucose is quantitatively detected in 100 microliters of human plasma with unprecedented sensitivity, as high as 104.51 ± 0.7 Hz·mM−1·cm−2 and a detection limit of 2.31 ± 0.3 mM. The results suggest the possibility to sense human plasma glucose at clinically relevant concentrations without the use of an external power source.

The author would like to acknowledge the funding support of “Efficient Conversion of Coal to Electricity-Direct Coal Fuel Cell” with the grant number “RFCR-CT-2011-00004” from the Research Fund for Coal & Steel of the European commission. CJ acknowledges the Royal Society of Edinburgh for a RSE BP Hutton Prize in Energy Innovation. Direct carbon fuel cells offer the opportunity of generating energy from coal at high efficiency as an alternative to the procedure of conventional power plants. In this study, raw anthracite coal and raw bituminous coal were investigated in a hybrid direct carbon fuel cell (HDCFC), which was a combination of a solid oxide fuel cell and a molten carbonate fuel cell. Mechanical mixing was confirmed to be an efficient method of mixing coal with carbonate. The coal samples had different properties, for example, carbon content, hydrogen content, volatile matter and impurities. The results showed that the maximum power density obtained by the cell with anthracite coal was similar to that obtained by the cell with bituminous coal. It was found that the total power output from coal in HDCFCs mostly depended on the carbon content, while volatile matter, hydrogen content, moisture, etc. had an effect on the short-term durability. HDCFCs were kept operating for more than 120 h with 1.6 g coal. This study demonstrates that energy can be generated efficiently by employing anthracite and bituminous coal in hybrid direct carbon fuel cells. Postprint

Efficient power density (EPD), defined as the ratio of efficient power to the maximum volume of working fluid, is taken as the objective for performance analysis and optimisation of an internally and externally irreversible radiative Carnot heat engine model from the viewpoint of finite-time thermodynamics or entropy generation minimisation. Maximising the value of EPD gives maximum efficient power density (MEPD). Results obtained are compared with those obtained using maximum efficient power (MEP) criteria, maximum power density (MPD) criteria and maximum power (MP) criteria. The results showed that the engine design at MEPD conditions has an advantage of smaller size and is more efficient than those designed at MP, MPD and MEP conditions.

Microbial fuel Cell (MFC) has gained a lot of attention in recent years due to its capability in simultaneously reducing organic component and generating electricity. Here multicultural rumen microbes (RM) were used to reduce organic component of slaughterhouse wastewater in a self-fabricated MFC. The objectives of this study were to determine the MFC configuration and to find out its maximum capability in organic degradation and electricity generation. The experiments were conducted by employing, different types of electrode materials, electrode size, and substrate-RM ratio. Configuration of MFC with graphite-copper electrode 31.4 cm2 in size, and substrate-RM ratio 1:10 shows the best result with current density of 318 mA m-2, potential 2.4 V, and achieve maximum power density up to 700 mW m-2. In addition, self-fabricated MFC also shows its ability in reducing organic component by measuring the chemical oxygen demand (COD) up to 67.9% followed by increasing pH from 5.9 to 7.5. MFC operating at ambient condition (29oC and pH 7.5), is emphasized as green-technology for slaughterhouse wastewater treatment. Article History: Received March 26, 2016; Received in revised form June 20, 2016; Accepted June 25, 2016; Available online How to Cite This Article: Prabowo, A.K., Tiarasukma, A.P., Christwardana, M. and Ariyanti, D. (2016) Microbial Fuel Cells for Simultaneous Electricity Generation and Organic Degradation from Slaughterhouse Wastewater. Int. Journal of Renewable Energy Development, 5(2), 107-112. http://dx.doi.org/10.14710/ijred.5.2.107-112

Cu–Co3O4 hybrids and activated carbon were employed to fabricate flexible solid-state electrochemical energy storage devices via facile processing. The resulting flexible devices showed a large specific capacitance of 530 mF cm−2 with excellent mechanical flexibility, which offered a maximum volumetric energy density of 0.71 mW h cm−3, and delivered a maximum power density of 88.6 mW cm−3. What's more, the device showed an excellent cycling stability with only ∼5.2% decay after 6000 cycles.

A macroporous monolithic ceramic anode material based on Magneli-phase titanium suboxides, fabricated by a facile method, is able to effectively generate bioelectricity in microbial fuel cells (MFCs). Owing to their highly active surface area and efficient extracellular electron transfer from electricigens to the anode, MFCs can achieve a peak biocurrent time of 37 h with a maximum power density of 1541 ± 18 mW m−2.

Cell temperature and selection of the reactant gases are crucial parameters for the design and optimization of fuel cell performance. In this study, effect of operating conditions on the performance of Solid Oxide Fuel (SOFC) has been investigated. Application of Response Surface Methodology (RSM) was applied to optimize operations conditions in SOFC. For this purpose, an experimental set up for testing of SOFC has been established to investigate the effect of Hydrogen, Oxygen, Nitrogen flow rates and cell temperature parameters on cell performance. Hydrogen flow rate, oxygen flow rate, nitrogen flow rate and cell temperature were the main parameters considered and they were varied between 0.25 and 1 L/min, 0.5 and 1 L/min, 0 and 1 L/min and 700-800 oC in the analyses respectively. The maximum power density was found as 0.572 W/cm2 in the experiments.

In this study, we demonstrate the effect of iron sheet on the output power of sediment microbial fuel cells (SMFCs). An SMFC with iron sheet present, but not in the circuit (SMFC-GF-iron) displayed a maximum power density of 63 mW m−2, whereas we find 37 mW m−2 for that SMFC with the iron sheet not present (SMFC-GF). Furthermore, the SMFC with an iron sheet in the circuit (SMFC-iron) had a maximum power density of 170 mW m−2. The effect of sheet iron, out of the circuit, was to improve the iron reduction microbial activity, while, within the circuit, it produced a large number of electrons from the electrochemical corrosion yielding higher power production. The study suggests that the addition of iron sheet to an SMFC is an easy and effective method for enhancing the output power of SMFCs.

The geometry of the flow channel in bipolar plates (BPs) significantly influences the performance of proton exchange membrane fuel cells (PEMFCs). Considering this, the present study is aimed at optimizing the flow field in a straight channel by pursuing a minimum entropy generation. In accordance with the optimization strategy established herein, the flow field in a straight channel was optimized by solving the governing equations using COMSOL. Furthermore, a novel M-like channel was designed. Compared with conventional wave-like channels, the M-like channel exhibits lower entropy generation under equal pumping power, which implies higher heat and mass transfer performance. An analysis of the four factors contributing to entropy generation revealed that the irreversibility resulting from the heat transfer process is higher than that from its three counterparts. To further improve the heat and mass transfer performance of the M-like channel, the effects of geometric parameters on the entropy generation were investigated. The polarization curves of the wave-like channel and M-like channel in a single fuel cell were obtained based on the fuel cell and electrolysis module. The numerical results indicated that the maximum power density of the M-like channel is higher than that of the wave-like channel by 21.3%. These results provide effective guidance for the geometric design of a flow field in the BPs of a PEMFC.

We present new architectures in CH3NH3PbI3 based planar perovskite solar cells incorporating solution processed SnO2/MgO composite electron transport layers that show the highest power outputs ever reported for photovoltaic cells under typical 200–400 lx indoor illumination conditions. When measured under white OSRAM LED lamp (200, 400 lx), the maximum power density values were 20.2 µW/cm2 (estimated power conversion efficiency, PCE = 25.0%) at 200 lx and 41.6 µW/cm2 (PCE = 26.9%) at 400 lx which correspond to a ∼ 20% increment compared to solar cells with a SnO2 layer only (even at standard 1 sun illumination, where the maximum PCE was 19.0%). The thin MgO overlayer leads to more uniform films, reduces interfacial carrier recombination, and leads to better stability. All layers of the cells, except for the two electrodes, are solution processed at low temperatures for low cost processing. Furthermore, ambient indoor conditions represent a milder environment compared to stringent outdoor conditions for a technology that is still looking for a commercial outlet also due to stability concerns. The unparalleled performance here demonstrated, paves the way for perovskite solar cells to contribute strongly to the powering of the indoor electronics of the future (e.g. smart autonomous indoor wireless sensor networks, internet of things etc).

Bioelectricity generated from the microbial fuel cell (MFC) is applied to the bioelectrical reactor (BER) directly to enhance microbial reduction of vanadium (V) (V(V)) in groundwater. With the maximum power density of 543.4 mW m −2 from the MFC, V(V) removal is accelerated with efficiency of 93.6% during 12 h operation. Higher applied voltage can facilitate this process. V(V) removals decrease with the increase of initial V(V) concentration, while extra addition of chemical oxygen demand (COD) has little effect on performance improvement. Microbial V(V) reduction is enhanced and then suppressed with the increase of conductivity. High-throughput 16S rRNA gene pyrosequencing analysis implies the accumulated Enterobacter and Lactococcus reduce V(V) with products from fermentative microorganisms such as Macellibacteroides . The presentation of electrochemically active bacteria as Enterobacter promotes electron transfers. This study indicates that application of bioelectricity from MFCs is a promising strategy to improve the efficiency of in-situ bioremediation of V(V) polluted groundwater.

This work is focused on the removal of sulphide from wastewater using a two chamber microbial fuel cell, seeded with activated sludge and operated in semi-continuous mode. Two co-substrates were used in order to provide the system for carbon and nutrient source: actual urban wastewater and synthetic wastewater. Results show that sulphide is efficiency depleted (removals over 94%) and that electricity is efficiently produced (maximum power density is 150 mW m−2) meanwhile COD is also oxidised (removals higher than 60%). Sulphur and sulphate are obtained as the final products of the oxidation and final speciation depends on the type of co-substrate used. The start-up of the system is very rapid and production of electricity and polarisation curves do not depend on the co-substrate.

Single-chamber microbial fuel cells (MFCs) using domestic wastewater (DWW) and milk processing wastewater (MWW) were operated at different organic loading rates (OLRs). The maximum power density (PDmax) and OLR (readily biodegradable COD [RBCOD] and soluble COD [SCOD]) followed the Lineweaver-Burk equation in all influents. The coefficients of determination were 0.9209 and 0.9975 for SCOD and RBCOD, respectively. OLR based on RBCOD showed better power generation function than that based on SCOD. PDmax (2.9-12.2 W/m(3)) in DWW was lower than that (6.9-24.9 W/m(3)) in MWW but the net energy recovery (kWh/kg-SCOD(removed)) in DWW (0.542-1.108) was larger than that in MWW (0.322-0.602). This was attributed to the higher ratio of RBCOD/SCOD (0.44) and the lower values of RBCOD (40 mg/L) in DWW, compared to RBOCD/SCOD (0.11) and RBCOD (110 mg/L) in MWW. Therefore, RBCOD is an important indicator for estimating power generation.

Pt/graphene-TiO2 hybrid catalysts have been synthesized by a facile one-pot solvothermal method. The Structural properties of obtained Pt/graphene-TiO2 catalysts are characterized by X-ray diffraction (XRD), Energy dispersive analysis of X-ray (EDAX) and transmission electron microscopy (TEM).Interesting, TEM presents Pt nanoparticles seem preferentially to locate between TiO2 and graphene, forming the unique triple junctions structure. The electrochemical experimental results indicate that Pt/graphene-TiO2 catalyst exhibits 1.46 times higher activity for methanol electrooxidation than that of Pt/graphene and its stability is improved by 15% as compared with Pt/graphene. Moreover, performance of Pt/graphene-TiO2 hybrid catalyst is evaluated by the Single Fuel Cell Tests for the first time. Single fuel cell tests show the maximum power density of the direct methanol fuel cell using Pt/graphene-TiO2 as the anode catalyst is increased by 55% compared with that using Pt/graphene catalyst at the same operating conditions. The significantly enhanced electrochemical performance can be ascribed to (1) the synergetic effect between Pt, graphene and TiO2; (2) strong metal-support interaction (SMSI) between Pt nanoparticles and TiO2. These findings suggest their great potential applications in fuel cells.

The aim of this study was to investigate the microbial stratification structure within cathodic biofilm of the microbial fuel cell (MFC) using the freezing microtome method. Experiments were conducted in a single-chamber air-cathode MFC with 0.8g/L maltodextrin as substrate for ∼30d operation. The maximum power density was 945±10mW/m2 in the MFC. Maltodextrin resulted in the relative abundance of Candidatus Saccharibacteria of 37.0% in the anodic biofilm. Different bacterial communities were identified in different layers within the cathodic biofilm. The relative abundance of Enterococcus was 3.7%, 10.5%, and 1.6% in the top (100-150μm), middle (50-100μm), and bottom (0-50μm) layers, respectively. Higher bacterial viability was observed within the top and bottom layers of the cathodic biofilm. Understanding the stratification of bacterial community in cathodic biofilm should be important to control the cathodic biofilm in the MFC.

Solid Oxide Fuel Cell is an attractive, efficient, alternative source of power generation. However several challenges remained for this technology to be viable. These challenges include high power density, degradation rate, and cost. One way to decrease the SOFC cost is to use stainless steel interconnector. To be able to use a stainless steel interconnector one of the challenges is to find a way to produce an electrolyte, which does not need sintering at high temperature. This work presents the results of the process applied to gadolinia-doped ceria thin films deposited in cycles by spray pyrolysis. The aim of this work was to obtain thin, dense, and continuous CGO coatings, which has electrochemical performance suitable to be used as electrolyte for SOFC. The results obtained show that the air flow rate influenced the droplets size and hence the film quality. X-ray diffraction analysis showed that the films were crystalline after the deposition. Electrochemical tests showed maximum power density of 510 mW cm-2 at 650 °C with a thickness average of 3.30 μm when the film was deposited in 12 cycles showing that the film has a potential to be used as an electrolyte for ITSOFC on metal support. © 2014 Elsevier B.V. All rights reserved.

Bioelectrochemically-assisted vermifilter (VBFBE) with sewage sludge as the anode fuel was constructed to accelerate composting of sewage sludge, which could increase the quality of the compost and harvest electric energy in comparison with vermicomposting and electrochemical only. Results revealed that the sludge stabilization with a higher soluble chemical oxygen demand (SCOD) and lower NH4+-H during 40 days of composting. At the composting, pH, C/N, electrical conductivity (EC) and germination index (GI) results demonstrated that the maturity degree of VBFBE4 was higher than that of other VBFBE. The VBFBE4 yielded a voltage of 1.024 V and maximum power density of 105.28 mW/m2 on 3th day. The bacteria in VBFBE4 were richer and higher in terms of diversity than those in other VBFBE, that was demonstrated that combination vermicomposting and electrochemistry could improve the sludge stabilization degree, accelerate sludge composting process and enhance composting maturity.

Triboelectric nanogenerators (TENGs), as a promising energy harvesting technology, have attracted considerable attention and various approaches have been developed to improve their output performance. An innovative strategy was proposed recently by using solid polymer electrolyte (SPE) with asymmetric pairing ions as the friction layer, showing excellent potential to achieve high-performance TENGs. However, it is far from clear what are the effects of SPE on TENG performance as only one electrolyte, CaCl2, was used for the investigation. Herein, PTFE/PVA-MClx TENGs based on SPEs with different types of electrolytes, including LiCl, ZnCl2, CaCl2, FeCl3, and AlCl3, were fabricated and their performances were investigated. All the devices demonstrated superior output performance than that of the control PTFE/PVA TENG. Specifically, the PTFE/PVA-LiCl TENG exhibited remarkably enhanced triboelectric performance with an output voltage of ~1345 V, a short-circuit current density of ~260 mA m−2 and a maximum power density of ~83 W m−2, four times higher than that of the control PTFE/PVA TENG. Detailed investigations revealed that in combination with improved triboelectric property, the enhanced interaction of SPEs with opposite triboelectric layers further significantly boost the triboelectric outputs. This work presents a new method to increase the interaction between triboelectric layers to effectively improve the outputs of TENGs, and to facilitate the development of high performance TENGs.

The aim of the present paper was to investigate the effects of hydraulic retention time (HRT) on the performance and microbial community dynamics of an anaerobic baffled reactor-bioelectricity Fenton (ABR-BEF) coupling reactor for treating traditional Chinese medicine (TCM) wastewater. The results show that the average removal of chemical oxygen demand (COD) and NH3-N at HRTs of 24 h and 18 h were high (>90% and >70%, respectively), but decreased to about 40% and 30% when operating at 12 h HRT. For the electrical production performance, the maximum power density was 196.86 mW/m3 at a HRT of 18 h. Methanomicrobia was the dominant archaea in the coupling reactor and the relative abundance of Methanothrix and Methanolinea increased with decreasing HRT. For the bacteria, the relative abundance of Planctomycetia significantly decreased with a short HRT; however, Anaerolineaceae was always the dominant bacterial taxa, which could guarantee efficient treatment of TCM wastewater.

The present study reports the design of a novel bioanode to deeply oxidize glucose in an enzymatic biofuel cell (EFC). This enzymatic glucose cell utilizes three co-immobilized enzymes: NAD-dependent glucose dehydrogenase (GDH), NAD(P)+-dependent gluconate-5-dehydrogenase (Ga5DH), and diaphorase (DI). Glucose is oxidized to gluconate by NAD-dependent GDH, gaining two electrons per glucose; the gluconate obtained as a by-product is oxidized at the C5 carbon to 5-keto-gluconate by Ga5DH. Operation of our bioanode enabled the oxidation of glucose in two stages, resulting in the gain of four electrons. The three-enzyme EFC provides a maximum power density of 10.51 ± 1.72 μW cm–2, which is about 1.6 times higher than the maximum power density of an EFC using a bioanode based on the co-immobilization of two enzymes (GDH and DI). Our results hold promise for increasing the current density of EFCs, and for application in glucose biosensor.

Microbial fuel cell (MFC) was studied as an alternate and a novel way to dispose food wastes (FWs) in a waste-to-energy form. Different organic loading rate obviously affected the performance of MFCs fed with FWs. The maximum power density of ~18 W/m(3) (~556 mW/m(2)) was obtained at COD of 3200±400 mg/L and the maximum coulombic efficiency (CE) was ~27.0% at COD of 4900±350 mg/L. The maximum removals of COD, total carbohydrate (TC) and total nitrogen (TN) were ~86.4%, ~95.9% and ~16.1%, respectively. Microbial community analysis using 454 pyrosequencing of 16S rRNA gene demonstrated the combination of the dominant genera of the exoelectrogenic Geobacter and fermentative Bacteroides effectively drove highly efficient and reliable MFC systems with functions of organic matters degradation and electricity generation.

To investigate functions and interactions of predominant microorganisms in microbial fuel cells (MFCs) for simultaneous electricity generation and Congo red decolorization, four strains were isolated from the anodic biofilm, and identified as Pseudomonas (M-P and I-P), Bacillus (M-B) and Aquamicrobium (I-A). Higher maximum power density (by 158.2% and 58.1%) but lower Congo red decolorization rate (by 3.2% and 5.9%) were achieved in MFCs using pure cultures I-P and M-P as inoculums than those using I-A and M-B, respectively. By comparing MFCs using co-cultures with those using pure cultures (M-P&B versus M-B and M-P, I-P&A versus I-A and I-P), the maximum power density of MFCs using co-cultures increased 82.0%, 15.1%, 94.6% and -24.6% (minus meant decreased), but decolorization rate decreased 33.3%, 29.4%, 7.9% and 5.0%, respectively. The results indicated specific interaction could enhance the performance of MFCs and might benefit the development of bio-process controlling.

Electrode materials are critical for microbial fuel cells (MFC) since they influence the construction and operational costs. This study introduces a simple and efficient electrode material in the form of palm kernel shell activated carbon (AC) obtained in tropical regions. The novel introduction of this material is also targeted at introducing an inexpensive and durable electrode material, which can be produced in rural communities to improve the viability of MFCs. The maximum voltage and power density obtained (under 1000 Ω load) using an H-shaped MFC with AC as both anode and cathode electrode material was 0.66 V and 1.74 W/m3, respectively. The power generated by AC was as high as 86% of the value obtained with the extensively used carbon paper. Scanning electron microscopy and Denaturing Gradient Gel Electrophoresis (DGGE) analysis of AC anode biofilms confirmed that electrogenic bacteria were present on the electrode surface for substrate oxidation and the formation of nanowires.

In this work, we presented the novel anode flow field for direct dimethyl ether fuel cell (DDFC). The anode flow field of the DDFC consisted of hydrophilic, hydrophobic, and diffusion region (with a ratio of region areas of 3:6:1). The maximum power density of the DDFC with novel anode flow field was 67 mW cm −2 , which was higher than that of the cell fed with conventional flow field (60 mW cm −2 ). The electrochemical impedance spectra analyses revealed that the mass transfer resistance of novel anode flow field was lower than that of conventional flow field. The constant current operation curves showed that the performance decay ratio of the novel anode flow field was lower than that of conventional one. It indicated that the novel flow field benefited the long-term operation of DDFC.

To make the polymer electrolyte membrane fuel cells (PEMFC) commercially viable, further reduction in cost and improvement in performance are required. In this work, an innovative design of a PEMFC with multiple catalyst layers (CLs) is considered and the design variables, weight fraction of platinum on carbon (f pt), platinum loading (m pt), ionomer loading (f ionomer) and thickness of all the CLs, are optimized for cost reduction and performance enhancement. In the first optimization study, the cell performance is maximized. The maximum current density of an optimized PEMFC with four CLs shows a significant improvement over the base case design at all operating voltages. In another optimization study, the platinum loading of the PEMFC with multiple CLs is minimized. With an increase in the number of catalyst layers, the platinum required to achieve the base case design current density is reduced. Using four CLs, a reduction of 17% (at 0.15 A cm -2) to 60% (at 0.7 A cm -2) in platinum loading is achieved in comparison to the base case design. In addition, the maximum power density of the PEMFC with multiple CLs is found to be superior to that of an optimized PEMFC with a single CL at all voltages. � 2012 Elsevier B.V. All rights reserved.

A cobalt-free Sm0.5Sr0.5FeO3−δ–BaZr0.1Ce0.7Y0.2O3−δ (SSF–BZCY) was developed as a composite cathode material for proton-conducting solid oxide fuel cells (H-SOFC) based on proton-conducting electrolyte of stable BZCY. The button cells of Ni-BZCY/BZCY/SSF–BZCY were fabricated and tested from 550 to 700 °C with humidified H2 (～3% H2O) as a fuel and ambient oxygen as oxidant. An open-circuit potential of 1.024 V, maximum power density of 341 mW cm−2, and a low electrode polarization resistance of 0.1 Ω cm2 were achieved at 700 °C. The experimental results indicated that the SSF–BZCY composite cathode is a good candidate for cathode material.

The role of functionalized multiwalled carbon nanotubes (MWNTs) decorated with platinum nanoparticles (Pt/f-MWNTs) and platinum-cobalt alloy nanoparticles (Pt 3Co/f-MWNTs) has been investigated for oxygen reduction reaction (ORR) in a proton exchange membrane fuel cell. The electrocatalysts are synthesized by a conventional sodium borohydride reduction method and modified polyol reduction method. The modified polyol reduction method yields better uniform dispersion, higher loading and optimum particle size of Pt and Pt 3Co alloy nanoparticles over the MWNTs compared to the conventional sodium borohydride reduction method. The electrochemical surface area of the electrocatalysts is calculated using cyclic voltammetry. Pt 3Co/f- MWNTs synthesized via modified polyol reduction method yield the highest performance with a maximum power density of 798 mW cm -2 at 60 �C without any back pressure. The enhanced catalytic activity of Pt 3Co/f-MWNTs toward ORR is attributed to uniform dispersion and optimum particle size of Pt 3Co alloy nanoparticles over the surface of f-MWNTs. � 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

In the present paper, the K2S2O8eFe 2þ system without pH adjustment was used as a cathodic reactant in a two-chamber microbial fuel cell (MFC) for the first time. The performance of the MFC with K2S2O8eFe 2þ system was discussed and compared with that of K2S2O8 and H2O2eFe 2þ system, respectively. These results demonstrated that the introduced ferrous ion could improve the power generation significantly. The initial K2S2O8/Fe 2þ molar ratios and the pH, which can affect the performance of MFC, were discussed later. The results revealed that K2S2O8eFe 2þ system achieved the best performance at K2S2O8/Fe 2þ molar ratios of 2:1 and the K2S2O8-Fe 2þ system was stable with varying pH value. This study demonstrated that the K2S2O8eFe 2þ system can be used as an

BaZr0.1Ce0.7Y0.2O3−δ (BZCY) electrolyte has been extensively studied as novel electrolyte for intermediate temperature solid oxide fuel cells (IT-SOFCs). In this short communication, we report our progress on the fabrication and characterization of the high performance anode supported BZCY cell. Maximum power density of 650 mW/cm2 at 700 °C is obtained for the single cell with configuration of Ni-BZCY/BZCY (20 um)/SSC-BZCY. Further, significant performance enhancement is observed during long-term stability test at 600 °C under constant voltage of 0.5 V, indicating excellent stability of BZCY under fuel cell operating condition. Those results indicate that BZCY based cell is very promising for practical applications.

This study investigates an aqueous solution of sulfuric acid that serves as the liquid electrolyte (LE) in a passive direct methanol fuel cell (DMFC). The addition of an LE can reduce methanol crossover and increase the fuel utilization significantly. To improve the performance of an LE-DMFC, a mathematical model is developed to optimize the thicknesses of both the LE layer and the Nafion membrane. The maximum power density of the LE-DMFC is improved by approximately 30% compared with a conventional DMFC (C-DMFC) when each is fed by methanol solutions of the same concentration. Due to the low methanol crossover of the LE-DMFC, a highly concentrated methanol solution can be directly fed into the LE-DMFC. The discharge time and volume energy density of the LE-DMFC are two times longer and three times greater than those of the C-DMFC, respectively. In addition, fuel utilization increases by approximately 100%.