The reporter learned from the University of Science and Technology of China that the team of Professor Yu Shuhong and the team of Professor Gao Minrui successfully developed a highly efficient oxygen evolution catalyst rich in cyano vacancies by bombarding traditional Prussian blue (PBA) materials with nitrogen plasma . This cyano vacancy can not only adjust the local electronic structure and metal coordination environment of the PBA material, but also effectively suppress the loss of iron active species during the electrical cycle. Related research results have been published in "Nature · Communication".
Oxygen evolution reaction (OER) is a key semi-reaction for new energy storage and conversion devices such as light / electrolyzed water and metal-air batteries. It is a very challenging issue to develop an inexpensive and efficient oxygen evolution reaction electrocatalyst to further reduce the electrode overpotential and improve the device energy efficiency. Material defect engineering can adjust the electronegativity, charge distribution and coordination environment of the catalyst, and is considered to be an effective strategy to improve the performance of the catalyst. Designing new defect structures and creating new forms of active sites is expected to further optimize the catalytic performance of existing catalytic materials.
Using nickel molybdate nanorods as a template, the researchers first prepared porous nickel iron-based PBA materials, and then bombarded them with nitrogen plasma to obtain PBA catalysts rich in cyano vacancies. Through various characterization methods, such as high-resolution transmission electron microscopy, positron annihilation technology, element content analysis, and exhaust gas absorption detection, etc., the formation of this new type of cyano vacancy was confirmed.
Electrochemical tests have shown that PBA samples bombarded with nitrogen plasma for 60 minutes show the best oxygen evolution reaction activity, far superior to other highly efficient oxygen evolution reaction catalysts. Structural analysis shows that this source of high oxygen evolution reaction activity Unsaturated nickel-iron sites induced by cyano vacancies. It was further found that the iron active species of PBA materials without cyano vacancies will gradually dissolve into the electrolyte. In sharp contrast, PBA containing cyano vacancies will greatly inhibit the loss of iron active species, thus self-reforming during the oxygen evolution reaction cycle to form a highly active surface active layer, which in turn leads to excellent OER activity and stability Sex.
This achievement provides a new strategy for the preparation of highly active nickel iron oxyhydroxide, and provides a new reference for the development of new types of defects, and provides a new idea for the design of more efficient oxygen precipitation catalysts in the future. (Reporter Wu Changfeng)
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