According to the report of the Physicist Organization Network on February 18 (Beijing time), researchers at the Pacific Northwest National Laboratory of the US Department of Energy for the first time used iron-based catalysts to split hydrogen gas rapidly and efficiently, which greatly reduced the cost of fuel cells. The research results were published in the latest issue of Nature & Chemistry online.
R. Morris Bullock, the lead chemist at the Center for Molecular Electrocatalysis, said that platinum is now used as a catalyst for fuel cells and its disadvantage is that the price is more than 1000 times that of iron. And his research team has developed and used cheaper metals, such as nickel and iron as catalysts, can quickly split hydrogen to two molecules per second, close to the efficiency of commercial catalysts.
Fuel cells use hydrogen to generate electricity from the electrons in chemical fuels: a large metal of platinum acts as a catalyst. Burst of a hydrogen molecule is like exploding an egg. White electrons, like egg whites, “pull out†currents. Because of the special chemistry of platinum to do this, chemists cannot simply replace this expensive metal with cheaper iron or nickel. However, a molecule that exists in nature known as "hydrogenase" can cause iron to split hydrogen.
Brock and his colleagues were inspired by the use of hydrogenase as a catalyst for hydrogenation. They first created several potential molecules for testing, and then determined the shape of the molecules for the best performance and adjusted the internal electrons for further improvement.
To do this, it is necessary to dissociate hydrogen molecules unevenly in the early process. Since a hydrogen molecule consists of two protons and two electrons, a proton must be dragged and sent by a catalyst before it is captured by a molecule called a proton acceptor. In an actual fuel cell, this receptor will be oxidized. Once the pulling force between the initial protons and their electrons dissipates, the electrode can easily get rid of the first electron. Then, another proton and electron are also removed, so that the two electrons will shuttle between the electrodes.
Through the experimental design, the team determined the speed at which the catalyst splits the hydrogen molecules. The highest value is about two molecules per second. In addition, the researchers also determined its overvoltage to measure the efficiency of the catalyst. The results show that overvoltages of 160-220 mV apparently already have commercial catalyst efficiencies. The research team is currently trying to slow down these reaction steps so that it can also speed up and determine the effectiveness of the catalyst under the best conditions. (Reporter Hualing epic)
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