Parameter Estimation for a Proton Exchange Membrane Fuel Cell Model Using GRG Technique

The parameter estimation of the proton exchange membrane fuel cell (PEMFC) model is important to accurately present the relationship between voltage versus current. Regarding this problem, the difference between observed voltage and model‐calibrated voltage, which composed of cell reversible voltage, activation voltage drop, ohmic loss, and concentration voltage drop, should be minimized. So far, various optimization algorithms have tackled this problem. However, there is still a way to improve the solution quality using another technique, and in order to fairly compare the solution qualities among the techniques, more information is required which has been so far missed. Thus, this study proposed generalized reduced gradient (GRG) technique which obtained good results. When compared with two variants of harmony search and two variants of particle swarm optimization, GRG could find much better results in terms of mean square error (MSE). Also, this study provided full problem formulation and numerical dataset, which was scattered in literature and not clearly provided in previous literature. Hopefully, this study invites more researchers to replicate this bench‐mark problem of the PEMFC parameter estimation and to tackle it using their own techniques in the future.     

Strategies for Dimensioning Two‐Wheeled Fuel Cell Hybrid Electric Vehicles Using Numerical Analysis Software

Owing to the limitation of fossil fuels and high consumption and pollution for transportation, the vehicle industry is looking for other sources of energy. A fuel cell hybrid electric vehicle (FCHEV) could be a suitable solution considering the state of the art of main components. This paper presents the simulation of powertrains for FCHEVs in order to dimension the fuel cell (FC) as primary source of energy and to investigate the power flows during both motoring and recuperative braking. For this purpose a Matlab/Simulink^® model has been built up which can be used for a wide range of applications. The results of simulation show which is the best powertrain configuration for two‐wheeled vehicles in three different cases: a bike in which the traction force is provided by both electric motor and the pedaling of the cyclist, a bike in which the traction force is provided only by an electric motor without pedaling and a motorcycle for 2 passengers. Specifically, the consumption, the state of charge (SOC) of battery and the amount of energy generated by each source of energy have been monitored. The model validation was done by comparison between the obtained results and scientific articles in the literature.     

Novel Metal Substrates for High Power Metal‐supported Solid Oxide Fuel Cells

Novel high permeable porous Ni‐Mo substrates with different area densities of straight gas flow channels are successfully developed to improve the hydrogen fuel gas and the water byproduct diffusion in the anode and supporting substrate. Metal‐supported cell A, cell B and cell C with 5 × 5 cm² supporting substrates are fabricated by atmospheric plasma spraying processes, these cells have the material structure of Ni‐Mo/LSCM (La_0.75Sr_0.25Cr_0.5‐Mn_0.5O_3–δ)/NiO‐LDC(Ce_0.55La_0.45O_2–δ)/SDC(Sm_0.15Ce_0.85O_3–δ)/LSGM (La_0.8Sr_0.2Ga_0.8Mg_0.2O_3–δ)/SSC(Sm_0.5Sr_0.5CoO_3–δ). Cell A is supported by a conventional porous Ni‐Mo substrate without straight gas flow channels, cell B and cell C are supported respectively by the novel high permeable porous Ni‐Mo substrates with 1.5 and 2.73 channels per square centimeter. The power densities at 0.8 V and 750 °C are 550, 998 and 1,161 mW cm⁻² for cell A, cell B and cell C respectively. The 100 h durability test at the constant current density of 400 mA cm⁻² and 650 °C shows cell B and cell C have smaller degradation rates than cell A. The results obtained from AC impedance and circuit model analyses indicate that the electrolyte ohm and the cathode polarization resistances are significantly reduced by introducing straight gas flow channels into the supporting substrate.     

Photosynthetic cathodes for Microbial Fuel Cells

One of the major limiting factors in the practical implementation of Microbial Fuel Cells is finding efficient and sustainable catalysts for the cathode half reaction, in an attempt to avoid expensive and/or toxic catalysts. The use of phototrophic organisms is one good option since they can act as efficient in-situ oxygenators thus facilitating the cathodic reaction. In the present study, the oxygen production by photosynthetic organisms was shown to be light dependant, which resulted in increasing the power generation by 42%. Furthermore, this study showed that a previously abiotic cathode that turned biotic showed a clear light response with an improved performance of 48%. Oxygen depletion in a water-based cathode can be avoided with the use of photosynthetic biocatalysts, thus providing sustainable operation for MFCs.     

The Vitality of Matter and the Instrumentalisation of Life

Artists and researchers Oron Catts and Ionat Zurr of SymbioticA, based at the School of Anatomy, Physiology and Human Biology at the University of Western Australia, are internationally renowned as pioneers in the field of biological arts, challenging audiences with their tissue engineering projects. Catts and Zurr discuss how synthetic biology has increasingly become ‘the new frontier for exploitation’ and why there is currently ‘a resurgence of the application of engineering logic in the fields of the life sciences’ in which life itself becomes a raw material.     

On the Catalytic Degradation in Fuel Cell Power Supplies for Long‐Life Mobile Field Sensors

Important tasks such as environment monitoring require field devices such as sensors that can operate for long durations. Current power supply technologies such as batteries limit many applications. Fuel cells are a promising alternative to batteries because they can have much higher energy densities. However, their lives may be short due to catalyst degradation. Here, a simplified model of proton exchange membrane (PEM) fuel cell catalyst degradation is applied to small fuel cells. The model focuses on the combined effects of catalyst dissolution and migration. The effect of migration on catalyst degradation is found to be substantial and this has not been accounted for in previous models. The model considers the effect of field conditions such as varying power demands, temperature and humidity, and predicts the catalyst life of the fuel cell and its power output. The predicted life is a proposed metric that can quantify the relative importance and effect of field conditions on the catalyst particularly for the design and control of fuel cell power supplies. Experiments are presented that support the model. This model is applied to a study on field sensors and results suggests unless PEM fuel cells are isolated from damaging field conditions, they will have short lives.     

In Situ Soft X‐ray Microscopy Study of Fe Interconnect Corrosion in Ionic Liquid‐Based Nano‐PEMFC Half‐Cells

This in situ soft X‐ray scanning microscopy electrochemical study of model proton exchange cathodic and anodic nano‐fuel cells is exploring the evolving structure and chemical composition of key cell components represented by Au and Fe electrodes in contact with Nafion‐ionic liquid composite electrolyte containing Pt black catalyst particles. Morphological and chemical changes of the electrodes as well as the chemical state and fate of the Fe species released into the electrolyte are monitored in short circuit and with applied cathodic or anodic polarization. The in situ X‐ray absorption images of the cathodic cell fed with 2.5 × 10^–5 mbar O₂ have revealed corrosion‐induced morphology changes in the Fe electrode, being more pronounced in the vicinity of Pt‐black particles, and deposition of the Fe species released into the electrolyte, onto the intact Au counter electrode upon cathodic polarization. The Fe electrodes of the anodic cell containing NaBH₄ in the electrolyte appear relatively more corrosion resistant. The Fe L₃ absorption spectra taken in different locations within the Fe electrode have shown lateral variations in the relative ratio between Fe²⁺ and Fe^3&4+ oxidation states, whereas the Fe species released into the RTIL electrolyte are only in the high Fe^3&4+ oxidation states.     

Dendronized Polymer Architectures for Fuel Cell Membranes

Multi‐step synthetic pathways to low‐ion exchange capacity (IEC) polysulfone (PSU) with sulfonic acid functionalized aliphatic dendrons and sulfonated comb‐type PSU structures are developed and investigated in a comparative study as non‐fluorinated proton exchange membrane (PEM) candidates. In each case the side chains are synthesized and introduced in their sulfonated form onto an azide‐functionalized PSU via click chemistry. Three degrees of substitution of each architecture were prepared in order to evaluate the dependence on number of sulfonated side chains. Solution cast membranes were evaluated as PEMs for use in fuel cells by proton conductivity measurements, and in the case of dendronized architectures: thermal stability. The proposed synthetic strategy facilitates exploration of a non‐fluorous system with various flexible side chains where IEC is tunable by the degree of substitution.     

Two‐Stage Oxidation of Glucose by an Enzymatic Bioanode

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.     

Adsorption of Sulfur‐Containing Species on LaCrO3 (001) Surface: A First‐Principles Study

Density functional theory calculations are employed to investigate the adsorption of sulfur‐containing species on the (001) surface of LaCrO₃ (LCrO). Molecular adsorption is found to be stable with H₂S binding preferentially at O site on the LaO‐terminated surface. The adsorption of H₂S molecule leads to the electrons transferring from the substrate to the molecule and the charges rearrangement within the molecule. In addition, the adsorption of the corresponding S‐containing dissociated species (SH and S) is investigated. SH and S are found to be preferentially bind at the Cr site. We further predict the adsorption energies of sulfur‐containing species increase following the sequence H₂S<SH<S for all the adsorption sites on LCrO (001) surface. Based on the adsorption energy comparison, LCrO is more sulfur‐tolerant than traditional Ni‐based anode materials, which is qualitatively in line with available experimental results. This study provides a scientific basis for rational design of sulfur‐tolerant anode materials for SOFCs.