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As we all know, hydrogen is a very clean and renewable energy source that can be stored and transported. Therefore, the use of solar energy to decompose water to produce hydrogen has become an attractive new energy technology. Semiconductor catalysts play a very important role in the photocatalytic production of hydrogen, including capturing light energy, reducing the reaction barrier, reducing energy consumption, and accelerating the reaction rate. As the most abundant and widely used semiconductor material on the earth, silicon has long been reported to be used for hydrogen production by photolysis of water.
Recently, Professor Xiong Yujie, a professor at the University of Science and Technology of China, for the first time revealed the mechanism of "hydrolysis of water to make hydrogen" on the surface of silicon nanowires, and provided a new way for the improvement of hydrogen production performance. The research results were published in "German Applied Chemistry" and selected as the hot paper of the journal. Dr. Liu Dong and Li Leilei, PhD students in the task force, were the co-first authors.
Researchers skillfully use micro-nano fabrication techniques (ie, top-down) and wet-chemical methods (ie, bottom-up) to highly selectively regulate the type and number of surface dangling bonds of silicon nanowire arrays. Based on system infrared spectroscopy monitoring, the research team was able to link photocatalytic hydrogen production efficiency and the average lifetime of excitons to the surface dangling bonds, thereby highlighting the key role of dangling bonds on the surface of silicon materials in photocatalytic applications.
On the other hand, the researchers found that the ratio of hydrogen and oxygen generated in this process is much higher than the stoichiometric ratio in conventional thinking, and therefore should be different from the traditional photocatalytic hydrogen production mechanism. Professor Jiang Jun's group undertook a theoretical simulation and confirmed not only the contribution of surface dangling to charge separation but also the chemical reaction barriers that occur on the surfaces of different dangling bonds. Based on the series of findings, the research team for the first time set aside the “veil†of the “hydrolysis of water by photolysis of silicon†mechanism and determined its reaction mechanism. After understanding the mechanism of action, researchers have developed a class of surface chemical processing methods based on conventional semiconductor industry technology that provides a simple way to regulate the state of dangling bonds on the surface of silicon nanowires and rationally modulate their photocatalytic hydrogen production. performance.
The research proposes a new surface engineering idea, paving the way for the development of efficient photocatalysts rich in the natural world, and will expand people's ability to control the "microscopic engine" of electron motion in chemical transformation, and has a rational design for efficient catalysts. Important role in promoting.
The research work was funded by the Ministry of Science and Technology's "973" program, the National Natural Science Foundation, the National Youth 1000 Program, the Chinese Academy of Sciences 100-person plan, a special research fund for higher education doctoral disciplines, and the university's important direction project development fund.
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