A new study shows that graphene manufactured in a special way can be used to make more durable hydrogen fuel cells for automobiles. According to foreign media reports, the research teams at Queen Mary University of London and University College London (UCL) used a special scalable technology to produce graphene and use it for research and development. Hydrogen fuel cell catalyst. Experiments show that, compared with existing catalysts, this graphene-based catalyst is more durable and has comparable performance.
(Image source: Queen Mary University of London)
The hydrogen fuel cell combines hydrogen and oxygen with the help of a catalyst to convert chemical energy into electrical energy. Since the only by-product of this reaction is water, it is an efficient and environmentally friendly energy source.
Among such hydrogen fuel cells, platinum is the most widely used catalyst, but its high cost is a big problem preventing the commercialization of hydrogen fuel cells. To solve this problem, commercial catalysts usually coat tiny platinum nanoparticles on a cheaper carbon carrier, but this material has poor durability and greatly shortens the service life of current fuel cells.
Previous studies have shown that graphene may be an ideal support material for fuel cells due to its corrosion resistance, large surface area and high conductivity. However, the graphene used in most experiments has many defects, which means that the expectation of improving its resistance has not been realized.
However, this time the researchers proposed a technique that uses one-pot synthesis to produce high-quality graphene coated with platinum nanoparticles. The process can be expanded for large-scale production, allowing graphene-based catalysts to be widely used in the energy field.
The researchers used the accelerated stress test recommended by the US Department of Energy (DOE) to conduct a large number of tests to confirm the durability of the graphene catalyst. Accelerated stress testing is deliberately in a short period of time to quickly force the catalyst in multiple cycles, so that scientists can evaluate the stability of new materials without testing fuel cells that have been running for months or years with this catalyst.
Using this type of test, the scientists found that the activity loss of the newly developed graphene-based catalyst was reduced by about 30% during the same test cycle compared with the commercial catalyst. (Yu Qiuyun)
External Cylindrical Grinding, cylindrical grinding is mainly carried out on an external cylindrical grinding machine, which is used to grind the outer cylinder, outer cone and shoulder end surface of shaft-type workpieces. During grinding, the workpiece rotates at a low speed. If the workpiece reciprocates in the longitudinal direction at the same time and the single-stroke or double-stroke movement in the longitudinal direction moves the grinding wheel relative to the workpiece, it is called longitudinal grinding.
Cylindrical grinding is mainly carried out on an external cylindrical grinding machine, which is used to grind the outer cylinder, outer cone and shoulder end surface of shaft-type workpieces. During grinding, the workpiece rotates at a low speed. If the workpiece reciprocates in the longitudinal direction at the same time and the single-stroke or double-stroke movement in the longitudinal direction moves the grinding wheel relative to the workpiece, it is called longitudinal grinding. If the width of the grinding wheel is greater than the length of the surface to be ground, the workpiece does not move longitudinally during the grinding process, but the grinding wheel continuously feeds the workpiece continuously, called the plunge grinding method. The efficiency of the plunge-cut grinding method is generally higher than that of the longitudinal grinding method. If the grinding wheel is trimmed into a forming surface, the plunge grinding method can be used to process the formed outer surface.
External Cylindrical Grinding
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