New bi-atomic material hydrogen-air fuel cell increases existing highest activity by 20%

Recently, iChEM researchers, Professor Wu Yuen's group from University of Science and Technology of China, and Associate Professor Chang Chunran from Xi'an Jiaotong University (corresponding author) successfully synthesized a diatomic Fe and Co immobilized on a porous nitrogen-doped nitrogen-doped nanomaterial for the first time using the dual-solvent method. Electrocatalysts on heterocarbons and the use of diatomic materials in hydrogen-air fuel cells and hydrogen-oxygen fuel cells. related results to“Design of N-Coordinated Dual-Metal Sites: A Stable and Active Pt-Free Catalyst for Acidic Oxygen Reduction Reaction”The title was published in the Journal of the American Chemical Society (J. Am. Chem. Soc., DOI: 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, so 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 generate water. It does not require charging and does not generate exhaust gas. The advantages such as friendliness have attracted people's attention and are considered to be the preferred clean energy power generation technology in the 21st century. Due to their unique electronic and geometric structures, diatomic catalysts often exhibit unexpected catalytic activities in some important chemical reactions. As the cathode catalyst of fuel cells, Fe, Co diatomic catalyst not only reduces the cost of the fuel cell catalytic layer, but also has a maximum output power density of 0.51 W cm-2 under the condition of loading less than 1 mg cm-2 for commercial platinum carbon of 76%. The research group of Prof. Wu Yuen used zinc-cobalt bimetallic MOFs as precursors to adsorb iron salts through a two-solvent method. In a high temperature environment, Fe3+ was gradually reduced by the surrounding graphitized C and bonded with adjacent Co to form Fe, Co bimetallic active site. At the same time, the Fe catalytic support generates nitrogen-doped graphitized carbon and decomposes the fragments releasing C and N, which accelerates the breaking of metal-imidazole-metal bonds, thereby forcing voids within the MOF. Eventually, the hollow structure was formed under the action of Kirkedall. Through spherical aberration electron microscopy, synchrotron radiation, Mössbauer spectroscopy and other means, the diatomic material is characterized by Fe, Co bonding and coordination with the surrounding N structure. Theoretical calculations show that the presence of Fe-Co bonds is more conducive to the cleavage of O-O bonds, and this structure enables the catalyst to have high activity in the oxygen reduction reaction. In the acid oxygen reduction reaction, it exhibited a half-wave potential of 0.863 V, an onset potential of 1.06 V, and a current density of 2.842 mA cm-2 at 0.9 V, and the excellent performance was stable for 50,000 cycles. The highest output power in hydrogen-oxygen fuel cells is as high as 0.98 W cm-2. In the hydrogen-air fuel cell, the highest output power is 0.51 W cm-2 and it operates stably for more than 100 hours. Among the non-Pt catalysts reported so far, this diatomic material has the highest performance for hydrogen-air fuel cells, and improves the existing highest activity by 20%. This research achievement has successfully applied the double atom catalyst as the cathode catalyst of the fuel cell, which greatly reduces the cost of the catalytic layer in the fuel cell. 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 vehicles brings new enlightenment. The above research work has been funded and supported by the National Natural Science Foundation of China and the Ministry of Science and Technology of the People's Republic of China.