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The new diatomic material hydrogen air fuel cell will increase the existing highest activity by 20%
Recently, iChEM researchers, the research group of Professor Wu Yuen of the University of Science and Technology of China, and Associate Professor Chang Chunran of Xi’an Jiaotong University (corresponding author) have successfully synthesized a diatomic Fe and Co immobilized on a porous nitrogen-doped by the two-solvent method for the first time. Electrocatalysts on heterocarbons, and diatomic materials are used in hydrogen air fuel cells and hydrogen-oxygen fuel cells. Related results were published in J. Am. Chem. Soc., DOI: 'Design of N-Coordinated Dual-Metal Sites: A Stable and Active Pt-Free Catalyst for Acidic Oxygen Reduction Reaction'. 10.1021/jacs.7b10385). The first author of the paper is Wang Jing, a doctoral student at the University of Science and Technology of China. With the development of human society, issues such as global energy consumption and climate change have attracted widespread attention. Therefore, it is urgent to find alternative clean energy. Among them, the fuel cell is a device that directly converts chemical energy into electrical energy through the electrode reaction of hydrogen and air to produce water. It does not require charging and does not produce exhaust gas. Because of the high energy conversion efficiency (up to 60%-80%) and the environment The superiority of friendliness has attracted people's attention, and it is considered to be the preferred clean energy power generation technology in the 21st century. Due to its unique electronic and geometric structure, diatomic catalysts usually exhibit unexpected catalytic activity in some important chemical reactions. Fe, Co diatomic catalyst as the cathode catalyst of the fuel cell not only reduces the cost of the fuel cell catalyst layer, but also has a maximum output power density of 0.51 W cm-2 when the load is less than 1 mg cm-2. It is commercial platinum carbon 76% of it. Professor Yuen Wu’s research group used zinc-cobalt bimetal MOF as the precursor to adsorb iron salts through the two-solvent method. Under high temperature environments, Fe3+ is gradually reduced by the surrounding graphitized C and bonds with adjacent Co to form Fe. Co bimetal active site. At the same time, the Fe catalytic carrier generates nitrogen-doped graphitized carbon, and decomposes and releases C and N fragments, accelerating the breaking of the metal-imidazole-metal bond, thereby forcing voids in the MOF. Eventually, a hollow structure was formed under the action of Kirkedall. Through spherical aberration electron microscopy, synchrotron radiation, Mössbauer spectroscopy and other methods, the structure of the diatomic material is characterized by the bonding of Fe and Co and coordination with the surrounding N. Theoretical calculations show that the existence of Fe-Co bonds is more conducive to the cleavage of O-O bonds, and this structure makes the catalyst highly active in oxygen reduction reactions. In the acidic oxygen reduction reaction, the half-wave potential is 0.863 V, the onset potential is 1.06 V, and the current density at 0.9 V is 2.842 mA cm-2, and the excellent performance of stable circulation is 50,000 cycles. The highest output power in the hydrogen-oxygen fuel cell is as high as 0.98 W cm-2. The highest output power in the hydrogen-air fuel cell is 0.51 W cm-2 and stable operation for more than 100 hours. Among the non-Pt catalysts that have been reported so far, the hydrogen-to-air fuel cell of the diatomic material has the highest performance and increases the existing maximum activity by 20%. This research result has successfully applied diatomic catalysts as the cathode catalysts of fuel cells, greatly reducing the cost of the catalyst layer in fuel cells. It is a major breakthrough in the field of fuel cells and provides the possibility for the commercial development of fuel cells. The development of battery cars has brought new enlightenment. The above-mentioned research work has been funded and supported by the National Natural Science Foundation of China, the Ministry of Science and Technology and other projects.
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