Maximiano V. Ramos

A technical review on gas diffusion, mechanism and medium of PEM fuel cell

The operation of polymer electrolyte membrane (PEM)-based fuel cells involves numerous physicochemical processes and components actively governing its function and, among them, gas transport phenomena and gas diffusion layer (GDL) are noteworthy, and the present paper provides a comprehensive assessment on gas diffusion mechanism, geometry of GDL components and related modelling studies involved in GDL fabrication. The impact of GDL on diffusion of reactants, water management and the transport of ions has also been systematically dealt.

The impact of anode design on fuel crossover of direct ethanol fuel cell

Direct-ethanol fuel cells (DEFCs) hold a promising future owing to its simple balance of plant operation and potential high-energy density. The significant challenges associated with it is the fuel crossover, which limits its performance and durability. In the present work, Pt–Pd nanocomposites were fused so as to find its impact on the anode design of DEFC. The current paper aimed to address these issues optimally and it also investigated the ethanol crossover by various electrochemical characterization techniques.

Manufacturing the Gas Diffusion Layer for PEM Fuel Cell Using a Novel 3D Printing Technique and Critical Assessment of the Challenges Encountered

The conventional gas diffusion layer (GDL) of polymer electrolyte membrane (PEM) fuel cells incorporates a carbon-based substrate, which suffers from electrochemical oxidation as well as mechanical degradation, resulting in reduced durability and performance. In addition, it involves a complex manufacturing process to produce it. The proposed technique aims to resolve both these issues by an advanced 3D printing technique, namely selective laser sintering (SLS). In the proposed work, polyamide (PA) is used as the base powder and titanium metal powder is added at an optimised level to enhance the electrical conductivity, thermal, and mechanical properties. The application of selective laser sintering to fabricate a robust gas diffusion substrate for PEM fuel cell applications is quite novel and is attempted here for the first time.

An improved electroactive polymer for optical applications

This paper investigates various experimental techniques of improving the optical properties as well as the electro-active characteristics of polyurethane polymer films for smart lens applications. Two experimental methods are used for preparing the films, the first consists of molding the polymer under various pressure and temperature conditions while the second is based on producing films of various thicknesses by the solvent casting method using tetrahydrofuran (THF) as solvent followed by a 100°C annealing in vacuum for 30min. Testing samples of 50 mm diameter are rigidly attached to circular frames and tested under applied field in the range of 30-80 kV/mm. The first method produces thicker and stiffer films with deformation response in the order of 0.8 mm; however, they are translucent. The second method results in thinner films with lower flexibility and reasonable electro-active response in the order of 0.3 mm. The transparency of the latter samples is excellent and closes the gap to produce a smart lens.

A Novel Fuzzy Schema to Control the Temperature and Humidification of PEM Fuel Cell System

The present paper proposes a simple yet effective technique to improve the performance of a practical PEM fuel cell system by tuning the two key operating parameters based on the expert’s rules derived from the literature. The fuzzy rule base is designed to optimally control the temperature and humidification of the two critical parameters governing the fuel cell system performance and dynamics. The modelling of the proposed methodology is presented through the Matlab/fuzzy logic toolbox.Copyright

A Novel 3D Printing Technique to Synthesise Gas Diffusion Layer for PEM Fuel Cell Application

Gas Diffusion Layer (GDL) is a versatile component of the PEM fuel cell stack and the well-known gas diffusion substrates used in the PEM fuel cell stack incorporates the carbon fiber based GDLs which suffers from limitations due to degradation and carbon oxidation. The present paper describes the novel integrated approach using 3D printed microfabrication technology to develop a durable, cheap and conductive gas diffusion material. Mechanical and Electrical characterization of the proposed material is performed which evidently indicates that the proposed material can be a promising candidate for gas diffusion layer in future.Copyright

Enhanced electromechanical performance of a functionalized carbon nanofiber/ionic liquid/electro-active paper composite

Trilayer actuators consisting of functionalized carbon nanofibers, ionic liquid and regenerated cellulose were fabricated simply by adopting a bimorph configuration with a regenerated cellulose-supported internal ionic liquid electrolyte layer sandwiched by electrode layers with a view to getting quick and long-lived operation in air at low applied voltages. The electrode layers include functionalized carbon nanofibers, ionic liquid and regenerated cellulose. The results indicate that the bending displacement decreases with increasing frequency and increases with increasing voltages. This actuator has a power density requirement of about 0.14 mW cm−2, which is achievable under microwave power, yet within radiation safety limits. The actuators exhibit larger displacement at lower voltages compared to the other CNF based actuators. In addition, the actuators can also be actuated electro-magnetically and responded well at higher frequencies compared to the actuators under electric field. The advantages of these types of actuators are an easy process of fabrication and they can be actuated remotely. Because of the electro-magnetic nature of actuation, one can also be beneficial from a contactless actuation that is not available in other actuation mechanisms like the electrostatic one.

Stretchable strain sensor facilely fabricated based on multi-wall carbon nanotube composites with excellent performance

In recent years, the increasing demand for flexible and wearable devices requires the synthesis of novel stretchable and piezoresistive materials. Piezoresistive polymer composites are popular due to their excellent piezoresistivity and high stretchability, which can readily be attached to clothes or human body. In this study, a stretchable and sensitive strain sensor based on multi-wall carbon nanotube (MWCNT)/polydimethylsiloxane (PDMS) composite with an excellent overall performance was fabricated in a facile and effective way. The composite with 7% MWCNTs is ideal for strain sensor compared to those with 5% and 9% MWCNTs. Not only can the gauge factor reach 5–9 under 10–40% strain, but also the curve of relative change in resistance versus strain is almost linear. The strain sensor can respond immediately with low hysteresis. The strain sensor also exhibits great stability under 1000 cycles of stretching/releasing, demonstrating the desirable long-term endurance to mechanical stimuli as well. The strain sensor was then implemented to monitor human motions (finger and wrist bending), precisely sensing the motion deformation and states. In conclusion, the reported sensor based on MWCNT/PDMS composite possesses numerous favorable characteristics including high sensitivity, good stretchability, ease of fabrication, and promising practical application in the field of biomedical system and wearable electronic devices.

Fast Release of Sulfosalicylic Acid from Polymer Implants Consisting of Regenerated Cellulose/γ-Ferric Oxide/Polypyrrole

This work presents a comparative study on the rate of drug release from implantable matrices induced by electric and magnetic fields separately for better biomedical applications. The matrices were prepared by coating γ-ferric oxide dispersed regenerated cellulose film by polypyrrole doped with sulfosalicylic acid as an anti-inflammatory drug. The drug release mechanisms were studied under both the electric and the magnetic fields separately in an acetate buffer solution with pH 5.5 and temperature 37°C during a period of 5 hours. The amount of drug released was analysed by UV-Vis spectrophotometry. The mechanism of drug release from the matrices under electric field includes expansion of conductive polymer chain and the electrostatic force between electron and drug. The drug release mechanism from the matrices under magnetic field is based on the fact that the heat produced locally by magnetic particles loosens the polymer (polypyrrole) chain surrounding the particles. As a result, the drugs attached to the polypyrrole chain come out to the release medium. The matrices showed fast release of drug, that is, more than 60% of the loaded drug was released within 1 h, and are ideal for the treatment of illness in an emergency care.

Preparation and characterization of a conductive polymer/electroactive paper actuator

In this paper, conducting polymer and ionic liquid cellulose electroactive paper composites (CPILEAPap is prepared and characterized. The CPIL_EAPap was prepared by dispersing ionic liquid in regenerated cellulose solution. The film obtained from the solution is then coated with polypyrrole electrodes. Electromechanical performance was assessed by measuring the bending displacement of the composite film. The bending displacement of the actuator was compared at different humidity conditions. In addition, morphological and structural studies were undertaken using FTIR and SEM analysis. Preliminary results show good displacement of the bender actuator which decreases with increasing % relative humidity. Additional work is being undertaken to further quantify and characterize the structural features that are important for actuation and humidification.