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Motor vehicles are the backbone of global transport. In recent years, due to the rising costs of fossil fuels and increasing concerns about their negative impact on the natural environment, the development of low-emission power supply systems for vehicles has been observed. In order to create a stable and safe global transport system, an important issue seems to be the diversification of propulsion systems for vehicles, which can be achieved through the simultaneous development of conventional internal combustion vehicles, electric vehicles (both battery and fuel cell powered) as well as combustion hydrogen-powered vehicles. This publication presents an overview of commercial vehicles (available on the market) powered by internal combustion hydrogen engines. The work focuses on presenting the development of technology from the point of view of introducing ready-made hydrogen-powered vehicles to the market or technical solutions enabling the use of hydrogen mixtures in internal combustion engines. The study covers the history of the technology, dedicated hydrogen and bi-fuel vehicles, and vehicles with an engine powered by a mixture of conventional fuels and hydrogen. It presents basic technology parameters and solutions introduced by leading vehicle manufacturers in the vehicle market. [ABSTRACT FROM AUTHOR]

Abstract: Proton-exchange membrane fuel cell (PEMFC) testing of Pt–Ru catalysts supported on differently prepared multiwall carbon nanotube (MCNT) supports was performed to elucidate the influence of the different supports on the operating characteristics of the catalysts under real direct methanol fuel cell (DMFC) anode and H2-PEMFC anode conditions. The MCNTs were either thin, entangled or thick, disentangled. Pretreatment of the MCNTs was also done and it was either high-temperature KOH etching or annealing (graphitization). The performance of the catalysts was compared against the performance of a commercial Pt–Ru catalyst supported on a high-surface-area carbon black. Among the different MCNT supports, the graphitized, entangled support offered the best performance in all tests, which was equal to the performance of the commercial catalyst, despite the MCNT catalyst layer was ca. 2.2 times thicker than the carbon black catalyst layer. Even for an MCNT catalyst layer, which was almost 7 times thicker than the carbon black catalyst layer, the transport limitations were not prohibitive. This confirmed the expected potential of nanotube supports for providing superior reactant transport properties of the PEMFC catalyst layers. [Copyright &y& Elsevier]

The fuel cell operation is associated with significant current density and durability problems, among other anode collectors. We used a numerical model based on flows with chemical reactions in a porous medium to solve these problems. We tested four variants of the anode channels. In the shape of the anode channel, we introduced changes to improve the current density. We also examined the influence of the channel shape on the stress field and rheological processes in the casing material. We verified the numerical model on the experimental data. Furthermore, we corrected the amount of the hydrogen stream and the produced water in the whole range of the cell's operation. The test results show that it is possible to increase the current density in all operating fields of the fuel cell while maintaining a low mechanical load on graphite elements and their safe operation time. [ABSTRACT FROM AUTHOR]

Abstract: Methanol adsorption and electro-oxidation on Pt-Rh alloys have been studied in aqueous 0.5M H2SO4 for a broad range of alloy surface composition including the pure Pt and Rh metals. Adsorption results have been compared with equivalent data obtained for CO and CO2 adsorption on these alloys. Current densities of continuous methanol oxidation on Pt, Rh and a Pt-Rh alloy with optimum surface molar fraction of Rh have been measured. Although on the pure Pt and Rh metals the methanol adsorption products exhibit similar energetic stability, as judged from the peak potential of electro-desorption, on the Pt-Rh alloys, there is a lowering of the stability. Similar behavior is observed for the CO and CO2 adsorption products, however, the lowering for methanol is much less than for CO and CO2. In the case of methanol, the maximum lowering is obtained for a surface molar fraction of Rh equal to ca. 0.65 and it is the same alloy surface composition that results in maximum lowering of the stability of the CO2 adsorption products, but not of the CO adsorption products (optimal fraction of Rh equal ca. 0.10). Structural similarity of the methanol and the CO2 adsorption products finds support in similar values of the electrons-per-site parameter obtained. Pt-Rh alloys show insufficient electrode potential improvement over Pt in continuous methanol electro-oxidation due to the susceptibility of Rh to strong poisoning by the methanol adsorption products, which switches off the bi-functional mechanism of methanol electro-oxidation on this alloy. The presence of Rh in the alloy with Pt additionally strongly lowers the methanol electro-oxidation turnover rate of the Pt component. [Copyright &y& Elsevier]

The operation of a fuel cell (PEMFC) is associated with severe problems related to individual components' local power density and durability. The problem arises from the unsatisfactory distribution of the H2 and O 2 reaction components and the high flow resistance. To find an answer to the problem posed, we tested nine variants of open anode/cathode channels dedicated to subsequent 3D printing. We have compared the obtained current-voltage characteristic curves with the experimental data of the fuel cell for which the new channels were dedicated. Each of the newly designed open flow channels had better current characteristics. Subsequently, we have compared selected cell properties between the best variants from the section. The final shape of the open channel ensured a high value of the current flux and local power density in the entire operating range of the fuel cell. Also, it generated low flow resistance allows for building a stack of cells. [Display omitted] • The size of the mesh determines the value of current-voltage characteristics. • The open porous channel was dedicated to the PEM fuel cell. • The complicated shape of the channel made it difficult to distribute the fluid. • A better distribution of the fluid components increased the current density. [ABSTRACT FROM AUTHOR]

Phloroglucinol/2-pyrrolaldehyde porous organic polymer impregnated with FeCl 3 was utilized to produce pyrolyzed iron-nitrogen-carbon (Fe−N−C) electrocatalysts for oxygen reduction reaction. The influence of the iron precursor content, addition of phenanthroline and pyrolysis temperature on the final Fe−N−C catalyst properties and activity were studied. The performance of the electrocatalysts obtained was additionally studied in a H 2 ‒air single-cell polymer electrolyte fuel cell (PEFC) with a ⁓4 mg (Fe−N−C) cm−2 cathode (5 cm2 membrane electrode assembly) and a Pt-based anode. The carbon gel-derived platinum group metal-free catalysts perform well in the PEFC achieving 0.2 W cm−2 and 0.37 A cm−2 at 0.5 V. The durability of the obtained Fe−N−C catalysts was also examined. [Display omitted] • Pyrolyzed Fe−N−C catalysts are produced from porous organic polymers (organic gels) • Pyrolysis at temperatures ≥850 °C yields catalysts with high activities • 3D architecture of Fe–N–C exhibits good transport properties in a H 2 −air fuel cell • Phenanthroline addition yields materials with enhanced graphitization and better durability • Fe–N–C catalysts achieve ⁓0.2 W cm−2 and 0.37 A cm−2 at 0.5 V in a H 2 −air fuel cell [ABSTRACT FROM AUTHOR]