 |
To many people, hydrogen is the most promising alternative to fossil fuels. However, the traditional way of producing pure hydrogen constrains the potential of hydrogen energy due to a number of problems. These problems include the production of large amounts of carbon dioxide in the production of hydrogen and the need for rare and expensive chemicals such as platinum.
Now, the above situation may be about to change radically. The reason is that scientists at the Brookhaven National Laboratory of the US Department of Energy have developed new electrocatalysts for the electrolysis of water. It uses relatively inexpensive materials to solve one of the problems in obtaining hydrogen from clean water. The nickel-molybdenum nitride catalysts they developed are nano-sheet structures that have opened up new effective hydrogen catalytic modes.
Traditional catalysts are too expensive
Water is an ideal resource for the production of pure hydrogen. It not only has abundant reserves, but also does not emit greenhouse gases during the production of hydrogen. However, the electrolysis of water to produce hydrogen and oxygen requires the addition of electrical energy and a catalyst that effectively destroys the chemical bonds of water molecules. In general, people want to obtain hydrogen gas at the same time, it is desirable to add as little energy as possible to help the electrochemical reaction.
For catalysts that promote the efficiency of electrolyzed water, it must be both durable, extremely active, and large in surface area. The strength of the affinity of the elements constituting the catalyst with hydrogen determines the ability of the electrolyzed water to react: the affinity is too weak and the reaction cannot proceed; the affinity is too strong and the initial activity will poison the catalyst.
In past practice, it has been recognized that the platinum electrocatalytic method has quite high efficiency in the decomposition of water to produce hydrogen. However, it is regrettable that the cost of platinum catalysts continues to rise. Platinum (which is currently priced at around US$50,000 per kilogram) and the high price of other precious metals are keeping investors on the sidelines. According to James Mukerman, head of the research program at the Brookhaven National Laboratory, people prefer platinum. However, the limited supply of the world not only causes the price of platinum to rise, but also makes people doubt its longevity. Maybe it cannot support the global hydrogen economy. development of.
Mukerman said that at the beginning, their goal was to mix a non-noble metal with a weak affinity for hydrogen with another non-precious metal with a strong affinity for hydrogen to obtain a highly active and stable catalyst. The focus is on the rich and inexpensive metal nickel and molybdenum. According to the current market conditions, nickel and molybdenum prices are 20 dollars and 32 dollars per kilogram respectively. After the two are combined, the price is 1,000 times lower than the price of platinum. Of course, for energy catalysts, people often think more about performance than price.
New Catalyst Mode Exploration
In the newly developed catalyst, nickel has replaced the position of platinum in the reaction, but its own electron density cannot be compared with platinum. In order to make up for the lack of nickel itself, scientists used molybdenum to enhance nickel's ability to react. Although this method is effective, it is still not comparable to platinum.
The first author of the research paper, Chen Weifu, introduced that in order to further improve the catalytic performance, they introduced the third elemental nitrogen to change the electronic states of nickel and molybdenum. Nitrogen has long been used in loose materials or materials with a size greater than 1 micron, but it is more difficult to use in nanosized materials. Initially, scientists hope to use nitrogen to change the structure of nickel molybdenum to form discontinuous spherical-like nanoparticles. But what's interesting is that they have new discoveries during the R&D process.
In the high-temperature ammonia environment, nitrogen was injected into the nickel-molybdenum composite. Scientists discovered that nickel-molybdenum nitrogen accidentally formed a two-dimensional nano-sheet with a large reaction area. Using high-resolution light microscopes from the Department of Condensed Physics and Materials at the Brookhaven National Laboratory and the National Synchrotron Radiation X-ray Detector, scientists figured out the two-dimensional structure and electronic arrangement of the new materials. According to Chen Wei-fu, this is the first time that people have obtained nano-sheet metal nitrides. The introduction of nitrogen has resulted in a huge change in the nickel-molybdenum composites. It has expanded the lattice of nickel-molybdenum alloys, increased the electron density, and made the electronic structure similar to precious metals. At the same time can prevent corrosion.
The performance of the newly developed catalyst is similar to that of the platinum catalyst, and it has the electrocatalytic activity and stability unmatched by any other non-precious metal compound. Mukerman said that the new catalyst production process is both simple and scalable, so that nickel-molybdenum nitride can have enough capacity to meet the needs of industrial applications.
The project's creator and chemist at the Brookhaven National Laboratory, Takataro Sasaki, said that they initially wanted to design an optimal catalyst with high activity and low price, capable of producing enough hydrogen as a high-density and clean energy source. The actual performance of the new catalyst exceeds their expectations.
Although the new catalyst does not mean that all problems of producing cheap hydrogen energy have been completely solved, it does reduce the cost of major electrolyzed water equipment. Scientists emphasized that their breakthrough stems from the exploration of basic knowledge, which is expected to change the entire research process, and the new model proposed will guide future research. (Reporter in the United States, Mao Li)
Petrochemical Pump,Petrochemical Process Pump,Petrochemical Centrifugal Pump,Petrochemical Industry Pump
Shenyang pump products sales co., LTD , https://www.syipsc.com