The team of Xiong Yujie, a professor at the University of Science and Technology of China, has made new progress again through cooperation with Professor Wu Xiaojun and Associate Professor Zhang Qun of the research team Luo Yi in material design and synthesis, theoretical simulation and advanced characterization. The researchers designed a semiconductor-metal composite structure with adjustable charge density, and revealed the competitive behavior and mechanism of the system's charge transfer during the activation of oxygen molecules, thereby obtaining an organic oxidation catalyst with significantly improved performance. The research results were published online in the "German Applied Chemistry" magazine recently. The co-first authors of the paper are PhD students Long Ran and Mao Keke.
Previously, organic chemists generally believed that semiconductor oxides, as carriers of metal catalysts, mainly act as catalyst templates in organic oxidation reactions. Based on the structure-activity relationship between the electronic state of the metal catalyst surface and molecular activation, the researchers proposed the idea and method of forming a composite structure between the metal nanocrystals and the semiconductor carrier. Through the effect of the Schottky barrier in the composite structure, the semiconductor photogenerated electrons migrate to the metal surface. So as to effectively regulate the surface electronic state. In this work, the researchers used ultrafast spectroscopy and kinetic measurements as probes for the first time, revealing that hot electrons caused by plasmons on the metal surface will be directly injected into the n-type semiconductor conduction band, which is driven by the Schottky barrier. Charge transfer forms a competitive relationship. On the basis of elucidating the microscopic mechanism of action, the researchers were able to optimize the activity of the catalyst in the activation of oxygen molecules and organic oxidation reactions through simple and effective means of light-emphasis control. This breakthrough research progress is helpful to deepen people's understanding of the design of photocatalyst composite materials, and is also of great significance to elucidate the principle of the widespread use of oxide supports in oxidation reactions in the organic chemistry community.
The above-mentioned research work was supported by projects such as the “973†plan of the Ministry of Science and Technology, the National Natural Science Foundation of China, the National Youth Thousand Talents Program, the Chinese Academy of Sciences Hundred Talents Program, and the China University of Science and Technology Important Project Cultivation Fund.
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