1,721,068 research outputs found
Realizing full potential of bioelectrochemical and photoelectrochemical systems
No full textIn this issue of Joule, the study by Lu et al. on spontaneous solar syngas production from CO2 driven by energetically favorable wastewater microbial anodes demonstrated a microbial photoelectrochemical system that combines oxidation of organic wastes in wastewater with photocathodic CO2 reduction reaction. Spontaneous CO2 reduction using the energy stored from sunlight and microorganisms incites the (bio)electrochemical system to the next stage by making CO2 reduction independent from additional energy sources.</p
Preparation and evaluation of a highly stable palladium yttrium platinum core–shell–shell structure catalyst for oxygen reduction reactions
No full textA core–shell–shell structure Pd–Y–Pt/C catalyst was prepared using a controlled surface reaction method. The structure was confirmed by X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray (EDX) techniques. Nano-scale yttrium was formed as a shell located as the middle layer of the catalyst. Electrochemical evaluation of the Pd–Y–Pt/C with less than 7% of Pt showed an improved performance toward oxygen reduction reaction (ORR) compared to Pt/C (20 wt.% Pt). Accelerated degradation tests (ADT) indicated that the addition of Y improved catalyst stability compared to Pt/C and Pd–Pt/C core–shell catalysts under various experimental conditions. This was due to the Y middle layer created approximate half-filled metal–metal d bond between Pt (or Pd) and Y. This catalyst utilized the core–shell–shell structure to minimize the Pt usage, and Y middle shell to improve stability
Resource recovery with microbial electrochemical systems
No full textMicrobial electrochemical systems consist of microbial fuel cells (MFCs), microbial electrolysis cells, and microbial desalination cells. They use an anode immobilized with microorganisms to oxidize organic matters in the wastewater and produce electrons. As the energy generation from MFCs is limited, more and more attention has been directed to reducing energy demand for wastewater treatment, and using cathode reactions, anoxic or aerobic, for recovering resources from waste.In this chapter, single and mixed metal ions recovery from various sources and concentrations using abiotic and biocathode in a bioelectrochemical system (BES) has been reviewed. Simultaneous metal recovery and electric energy generation was possible for the metals with more positive reduction potential than copper (0.34V, standard hydrogen electrode). Electrodeposition electroprecipitation and biosorption are the main mechanisms for metal removal and recovery. Nutrients, mainly nitrogen and phosphorous, removal and recovery have been discussed. Nitrogen recovery is mainly in the form of ammonia recovery, whereas phosphorous recovery is by forming struvite precipitation (MgNH4PO4·6H2O) by adding magnesium and ammonia at the cathode of BES.Electrochemical reduction of CO2 to produce various simple organic compounds is largely dependent on the catalysts chosen. With electrons/electric energy produced from microbial anode in BES, the overall energy for CO2 reduction can be reduced. Microbial electrosynthesis opens up a new avenue on synthesizing medium chain organic compounds with chain elongation process.BES combining waste treatment and extracting energy and recovering resources from waste is a promising technology for sustainable chemical and fuel production, and will have positive impact on the environment and society.</p
Development of direct methanol alkaline fuel cells using anion exchange membranes
No full textResearch into the development of direct methanol alkaline fuel cell (DMAFC) using an anion exchange polymer electrolyte membrane is described. The commercial membrane used had a higher electric resistance, but a lower methanol diffusion coefficient than Nafion® membranes. Fuel cell tests were performed using carbon supported Pt catalyst, and the effect of temperature, methanol concentration, methanol flow rate, air pressure and Pt loading were investigated. It was found that the cell performance improved drastically with a membrane assembly electrode (MEA) which did not include the gas diffusion layer on the anode, because of lower reactant mass transfer resistance. To give suitable cathode performance, humidification of the air and a subtle balance between the air pressure and water transport is required.</p
Direct methanol alkaline fuel cell with catalysed metal mesh anodes
No full textPlatinised Ti electrodes were produced by thermal decomposition of H 2PtCl6 onto mesh substrates. Surface properties and morphology of the Pt deposit on Ti mesh were characterised using SEM, EDAX and XRD analysis. A highly dispersed Pt deposit layer was obtained. Direct methanol fuel cell tests with anion exchange membrane electrolyte and platinised Ti mesh anode were carried out and compared to conventional hot-pressed carbon supported Pt catalysts. The platinised Ti mesh anode showed higher catalytic activity than the conventional Pt/C electrode, and gave a stable fuel cell performance.</p
Microbial electrochemical and fuel cells: fundamentals and applications
No full textMicrobial Electrochemical and Fuel Cells: Fundamentals and Applications contains the most updated information on bio-electrical systems and their ability to drive an electrical current by mimicking bacterial interactions found in nature to produce a small amount of power. One of the most promising features of the microbial fuel cell is its application to generate power from wastewater, and its use in the treatment of water to remove contaminants, making it a very sustainable source of power generation that can feasibly find application in rural areas where providing more conventional sources of power is often difficult. The book explores, in detail, both the technical aspects and applications of this technology, and was written by an international team of experts in the field who provide an introduction to microbial fuel cells that looks at their electrochemical principles and mechanisms, explains the materials that can be used for the various sections of the fuel cells, including cathode and anode materials, and provides key analysis of microbial fuel cell performance looking at their usage in hydrogen production, waste treatment, and sensors, amongst other applications. Includes coverage of the types and principles of electrochemical cells. Provides information on the construction of fuel cells and appropriate materials. Presents the latest on this renewable source of energy and the process for the treatment of waste water.</p
A direct glucose alkaline fuel cell using MnO <sub>2</sub>-carbon nanocomposite supported gold catalyst for anode glucose oxidation
No full textGold nanoparticles supported on MnO 2-carbon nanocomposite (Au/MnO 2-C) are synthesised as the catalyst for the anodic oxidation of glucose for use in a direct glucose alkaline fuel cell (DGAFC). Characterisation of the catalyst is carried out using physical and electrochemical methods. It is observed that gold nanoparticles are uniformly dispersed onto the MnO 2-carbon nanocomposite support. Cyclic voltammetry shows that the prepared Au/MnO 2-carbon catalysts exhibit higher electro-catalytic activity for glucose oxidation than that of commercial Pt/C and Au/C catalysts. A maximum power density, at 30 °C, of 1.1 mW cm -2 is obtained using an Au/MnO 2-C anode catalyst in DGAFC, which is higher than that of the commercial Au/C catalyst. The enhanced activity is attributed to a catalytic effect of MnO 2 towards glucose oxidation. MnO 2-C nanocomposite is a promising approach for reducing noble metal catalyst loading in addition to improving the catalytic activity of gold catalyst for glucose oxidation.</p
Enzymatic Biofuel Cells—Fabrication of Enzyme Electrodes
No full textEnzyme based bioelectronics have attracted increasing interest in recent years because of their applications on biomedical research and healthcare. They also have broad applications in environmental monitoring, and as the power source for portable electronic devices. In this review, the technology developed for fabrication of enzyme electrodes has been described. Different enzyme immobilisation methods using layered structures with self-assembled monolayers (SAM) and entrapment of enzymes in polymer matrixes have been reviewed. The performances of enzymatic biofuel cells are summarised. Various approaches on further development to overcome the current challenges have been discussed. This innovative technology will have a major impact and benefit medical science and clinical research, healthcare management, energy production from renewable sources
Influence of temperature and other system parameters on microbial fuel cell performance: numerical and experimental investigation
No full textThis study presents a steady state, two dimensional mathematical model of microbial fuel cells (MFCs) developed by coupling mass, charge and energy balance with the bioelectrochemical reactions. The model parameters are estimated and validated using experimental results obtained from five air-cathode MFCs operated at different temperatures. Model analysis correctly predicts the nonlinear performance trend of MFCs with temperatures ranging between 20 °C and 40 °C. The two dimensional distribution allows the computation of local current density and reaction rates in the biofilm, helping to correctly capture the interdependence of system variables and predict the drop in power density at higher temperatures. Model applicability for parametric analysis and process optimization is further highlighted by studying the effect of electrode spacing and ionic strength on MFC performance.</p
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