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Herein, Pd and a series of PdZn bimetallic nanoparticles supported on Vulcan XC-72 carbon were prepared by ultrasound-assisted NaBH4 impregnation-reduction method for the oxidation reaction of BH4- (BOR). The physical properties of the electrocatalysts were identified by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and inductively coupled plasma optical emission spectrometry techniques. The electrochemical properties were characterized by cyclic voltammetry, chronoamperometry and linear sweep voltammetry (LSV). The results were indicated uniformly dispersed PdZn nanoparticles on carbon with an average particle size of 5 nm. The number of electrons calculated from LSV data was found to be in the range of 3.0-3.5. Among all the prepared catalysts, PdZn-01/C exhibited the highest current density (1818 mA mg(Pd)(-1)) and stability towards BOR.

Fuel cells are promising alternative energy converters in terms of preventing pollution, efficiency, and noise. Direct borohydride fuel cells (DBFCs) which are defined as a sub-class of polymer electrolyte membrane fuel cells (PEMFCs) and direct liquid fuel cells (DLFC) have increased attention recently since they offer a solution for hydrogen storage problem. However, the commercialization of DBFC is hindered by the need of high platinum loadings. Therefore, reducing the platinum content is crucial to develop cost-effective DBFC without compromising performance. This research focuses on the effects of operational parameters on the DBFC performance with low level Pt/C catalyst loading (anode: 0.32 mg/cm(2), cathode: 0.36 mg/cm(2)). The gas diffusion electrode was prepared by spray-coating technique. The peak power density of 19.95 mW/cm(2) was obtained at 80 degrees C when 1 mL/ min was used as a flow rate of fuel. (c) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Fuel cells (FCs) have been mentioned as an alternative energy technology in which the chemical energy of the fuel is directly converted into electrical energy. Fuel cell technology is progressing gradually with intense researches in the fields of material engineering, nanotechnology, transport phenomena, electrocatalysts engineering, etc., and it is now possible to use these systems in many stationary and portable applications. This chapter consists of four subsections. In the first part, a brief introduction to the history of fuel cells was given. Subsequently, the information on the development of fuel cell technology and the current state of these systems in recent years will be provided in the second part. The third part was dedicated to basic components of fuel cells (on the specialty of PEMFC). The last part was concerned about the basis of direct liquid fuel cells (DLFCs) in which the fuel (alcohols, acids, glycols) is in liquid form.

Among the liquid fuels that can be utilized for direct liquid fuel cells (DLFCs), inorganic fuels can be analyzed in a separate class. The reason for this is mainly the lack of carbon–carbon bonds and carbon atoms (except a few exceptions) in their chemical structures. The basic advantage of this is the elimination of carbon dioxide as a product. Since the oxidation kinetics and mechanisms will be different because of the lack of C C bonds, the analysis and development will be different compared to other organic liquid fuels. The details of these, especially in terms of catalysts and kinetics will be explained in the following chapters. In this chapter, basic information about sodium borohydride, hydrazine, hydrazine hydrate and ammonium borane which are the main inorganic fuels investigated for DLFCs up to date in the literature was given. The chemical, physical and thermodynamic properties, potential hazards, advantages and disadvantages of these fuels were summarized as well as the publication statistics up to date. Sodium borohydride is by far the most widely studied one among the others for its high energy density and high open-circuit potential but has its own drawbacks such as the difficulty in recycling the product sodium metaborate and also because of the high cost of fuel. Each fuel has its own drawbacks and advantages from different points of views as was discussed in the chapter.

Direct liquid fuel cells (DLFCs) have potential advantages especially for portable and mobile applications over hydrogen-based fuel cells due to their higher theoretical energy density, easy handling and safe-low cost storage. The research numbers, number of fuels researched and interest from both academia and industry are increasing regularly with the advancements and commercialization of conventional FC technologies such as PEMFC and SOFC. Each fuel has its own advantages and drawbacks. In this book, the fuels and DLFC studies up-to-date were explained in detail in the related chapters. One objective was also to bring them together with a consistent classification system. This chapter gives a review of the fuels and a summary of the current state, recent trends (statistics) and the challenges for the development of DLFCs, with special emphasis on the most critical components, the catalysts and ion exchange membranes, as well as other components.

In this study, the effects of Ag, ZnO, and CuO nanoparticles (NPs) on the mechanical, thermal, and biodegradability properties of the compatibilized polyethylene (PE)/thermoplastic starch (TPS) blends were investigated. Polyethylene-grafted maleic anhydride (PE-g-MA) was used as the compatibilizer. The compatibilized PE/TPS blends with different NPs were prepared by melt mixing method in a laboratory scale extruder and then pressurized in the press machine. The use of ZnO NP together with the compatibilizer in PE/TPS-based films significantly increased the tensile stress values. The use of different type NPs did not cause any significant change in the thermal stability of PE/TPS-based films. However, the effects of NPs were observed on the TPS degradation steps. The prepared films with different NPs showed an antibacterial activity between 60% and 70%. The highest crystallinity value was obtained in Ag NP containing films, among others. According to scanning electron microscopy analysis, better distribution was observed for ZnO and Ag NPs than CuO NP. In general, it can be said that the addition of NPs to PE/TPS-based blends significantly reduces the partial biodegradability of the resulting films. Kocaeli UniversityKocaeli University Kocaeli University WOS:000640617800001 2-s2.0-85104369151

Direct Borohydride Fuel Cell (DBFC) is one of the most promising liquid fuel cell technologies. However, similar to the other classes of fuel cells, there are technical problems to be solved and new materials specific to the technology should be developed for each component. The electrolyte membrane is one of the key components for its success similar to the other FC types. Commercial perfluorosulfonic acid type membranes namely Nafion (R) is still the first choice in relatively less number of DBFC studies. In this study, less costly blend membranes were fabricated and characterized for comparison of the key properties with Nafion (R) especially for DBFC application. For this purpose, the selected base polymer poly ether-ether-ketone (PEEK) was sulfonated up to high degrees of sulfonation (DS) and blended with another base polymer polybenzimidazole (PBI) at various ratios. Key electrolyte membrane properties such as DS, water uptake, ionic conductivity, BH4+ fuel crossover, mechanical strength and glass transition temperature (T-g) were investigated by proton nuclear magnetic resonance spectroscopy (H NMR), electrochemical impedance spectroscopy (EIS), voltammetry, universal testing machine and Differential Scanning Calorimetry (DSC) respectively. Finally single cell test performances were investigated in a DBFC test system. Results showed that the mechanical strength of SPEEK which has a good ionic conductivity value could be improved well beyond the value of Nafion 117 without sacrificing too much of the conductivity. It has been observed that there is a trade-off between the important properties such as ionic conductivity, fuel (borohydride) permeability and mechanical strength at the first sight. The peak power densities obtained for blend membranes are close to the value of the commercial Nafion (R) 117 membrane. These results show that these blend membranes have a potential that can be improved for direct borohydride fuel cells. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

In this study, composite cation exchange membranes (CEM) were developed. With the experience from widely studied proton exchange membrane fuel cells (PEMFC), sulfonated polyether ether ketone (SPEEK) was prepared to be a more effective and cheaper ionomer alternative to the industry standard Nafion (R). SPEEK polymer membrane can reach sufficient ionic conductivities but have some mechanical and chemical stability problems (at a high degree of sulfonations (DS)). Therefore, in order to optimize the membrane, composite mixing with a well-known organic/inorganic clays called Cloisite (R) 15A, Cloisite (R) 308 and MMT were used. Test cells for both single-cell and conductivity were designed and constructed. The ionic conductivity cell was different than the ones used in most studies, measuring conductivity in-plane with 4 probes using EIS. The membranes were characterized for their proton conductivity with electrochemical impedance spectroscopy (EIS), for DS with H NMR, water uptake, and fuel cell performance tests. First results showed that the acidic sulfonic groups of SPEEK interacted with organic/inorganic clays and as a result of partial barrier the ionic conductivity was decreased but power densities were increased. SPEEK-Cloisite (R) 30B composite membrane has given 40 mW/cm(2) power density value which is higher than pure SPEEK membrane (35 mW/cm(2)). The proton conductivities of the final composite membranes were close to bare SPEEK membranes which are 0,065 and 0,075 S/cm for SPEEK-Cloisite (R) 30B and pristine SPEEK, respectively. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.