Catalysts accelerate chemical reactions, but widespread metal platinum is scarce and expensive. Researchers at the Technical University of Eindhoven (TU / e) have now developed an alternative with 20-fold higher activity in collaboration with Chinese, Singaporean and Japanese researchers: a catalyst with hollow nanocages made from an alloy of nickel and platinum. With this new catalyst, TU / E researcher Emiel Hensen wants to develop an electrolyzer with a refrigerator size of around 1
By 2050, the national government aims to cover almost the entire energy needs of the Netherlands from sustainable sources such as the sun or the wind. Since these energy sources are not always available, it is important to be able to store the energy produced. Due to their low energy density, batteries are not suitable for storing very large amounts of energy. A better solution is chemical bonding, where hydrogen is the most obvious gas choice. An electrolyzer converts water (an excess of) electrical energy into hydrogen, which can be stored. At a later stage, a fuel cell does the opposite and converts the stored hydrogen back into electrical energy. Both technologies require a catalyst to drive the process forward.
The catalyst that aids in these reactions is mostly platinum because of its high activity. Platinum, however, is very expensive and relatively rare; a problem if we want to use electrolysers and fuel cells on a large scale. TU / e catalysis professor Emiel Hensen: "Researchers from China have therefore developed an alloy of platinum and nickel that lowers costs and increases activity." An effective catalyst has a high activity; every second, it converts more water molecules into hydrogen. Hensen: "At TU / e, we studied the influence of nickel on key reaction steps by developing a computer model based on images from an electron microscope, and using quantum chemical calculations, we were able to predict the activity of the new alloy and we could Understand why this new catalyst is so effective. "
Successfully tested in a fuel cell
In addition to the other choice of metal, researchers were also able to produce significant changes to the morphology. The atoms in the catalyst must combine with the water and / or oxygen molecules in order to convert them. More binding sites therefore lead to a higher activity. Hensen: "They want to provide as much metal surface as possible, and the hollow nanocages they create can be accessed from the outside as well as from the inside, creating a large surface area that allows more material to react simultaneously." "In addition, Hensen has shown by quantum chemical calculations that the specific surface structures of the nanocages increase the activity even further.
According to calculations in the Hensen model, the activity of both solutions is 20 times higher than that of the current platinum catalysts The researchers also found in experimental tests on a fuel cell. "An important criticism of many fundamental work is that it works in the lab, but if someone puts it in a real device, it often does not work. We have shown that this new catalyst works in a real application.
The stability of a catalyst must be such that it can continue to work for years in a hydrogen car or house, so the researchers tested the catalyst for 50,000 "rounds" in the fuel cell and found a negligible decrease in activity. [19659005 Electrolyzer in each district
The possibilities for this new catalyst are manifold, both in the form of the fuel cell and the reverse reaction in an electrolyzer, for example, fuel cells are used in hydrogen-powered cars, while some hospitals already have emergency generators For example, an electrolyzer can be used in offshore wind farms or even next to any wind turbine, transporting hydrogen is much cheaper than transporting electricity.
Hensen's dream goes further, saying, "I hope that we will be in every city soon Part can install an electrolyzer. This refrigerator-sized appliance stores the entire energy of the solar panels on the rooftops of the district as hydrogen throughout the day. The underground gas pipelines will do it "in the future transport hydrogen, and the domestic boiler will be replaced by a fuel cell, which converts the stored hydrogen back into electricity, so that we can make optimal use of the sun."
The electrolyzer still needs to be developed significantly become. Together with other TU / e researchers and industry partners from the Brabant region, Hensen is therefore involved in the start-up of the Energy Institute of the Eindhoven University of Technology. The aim is to scale the current commercial electrolyzers to a refrigerator-sized electrolyzer of about 10 megawatts.
Study shows that a much cheaper catalyst can produce hydrogen in a commercial device
"Technical Bundled Pt-Ni Alloy Nanocages for Efficient Oxygen Reduction in Practical Fuel Cells" Science (2019). science.sciencemag.org/cgi/doi… 1126 / science.aaw7493
20 times more effective storage of energy in hydrogen with platinum-nickel catalyst (2019, 14 November)
retrieved on November 14, 2019
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