Recently, Liu Qinghua, associate researcher at the National Synchrotron Radiation Laboratory of the University of Science and Technology of China, Dr. He Jinfu and associate researcher Yao Tao used synchrotron radiation x-ray absorption spectroscopy (xafs) technology to regulate the structure and performance of new solar energy conversion functional materials. New progress was made, and the results of the research were published in the "Nature-Communications" on October 6th.
In view of the scientific problem of low water-decomposing performance of metal oxides in the visible light region, the researchers proposed a way to guide the migration of photogenerated carriers by forming energy level structures of “vector migration channelsâ€.
Experimentally, a layer of 2~3nm thick fe2tio5 narrow bandgap (2.2ev) semiconductor material was coated on the surface of a highly ordered tio2 nanotube array to form a carrier separation interface between fe2tio5/tio2. The photogenerated holes are migrated from the interior of the material to the reactive sites on the surface of the surface. At the same time, the conduction band structure of fe2tio5 and tio2 greatly reduces the overpotential of the water decomposition reaction, making the fe2tio5-tio2 composite structure at 400-600 nm. The quantum conversion efficiency in the wavelength range is as high as 40% and the total energy conversion efficiency is 2.7%.
The researchers also used a series of measurements and theoretical analysis such as synchrotron radiation x-ray absorption spectroscopy and electrochemical impedance spectroscopy to confirm that the "vector migration channel" energy level structure at the fe2tio5-tio2 interface is the reason for the direct migration of photogenerated carriers. .
This work enriches people's understanding of the use of energy band engineering to improve the visible light quantum efficiency of photolysis water, and provides new ideas for further regulating the water-decomposition performance of oxide semiconductor photocatalysts. The reviewer believes that the method of carrier separation proposed in this work and the way to reduce the initial decomposition potential of water through energy level cutting have very important potential significance in the field of solar water decomposition.
The above research was funded by funds from the National Natural Science Foundation of China, the Innovative Research Group Project and the "973" Project of the Ministry of Science and Technology.
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