With the rapid socio-economic development taking place in China, the excessive consumption of fossil fuels has resulted in a large amount of carbon dioxide emissions, leading to a global energy and environmental crisis. To solve this problem, chemical engineering scientists have committed to the usage of solar energy and semiconductor photocatalysts, with a view to developing "artificial photosynthesis”. By transformation of the carbon dioxide and water into hydrocarbons or hydrogen, the carbon cycle can be realized and new energy development and utilization can occur. Over the years, with the support of the National Natural Science Foundation of China, Prof. Gong Jinlong of the School of Chemical Engineering and Technology at Tianjin University, has improved the efficiency of artificial photosynthesis by modifying and improving the catalyst.
Innovation of a Scientific Principle
The promotion of electron-hole separation and transport in the catalyst and the improvement of the carrier reaction rate on the catalyst surface have become an important research target in the artificial light synthesis field.
"We want to efficiently stimulate the formation of electrons, which would selectivity participate in the water or carbon dioxide reduction reaction, and the particular nanostructure of the catalyst would help increase the occurrence of the reduction reaction." Gong Jinlong told the "China Science Daily" reporter, "thus to realize the efficient conversion of solar energy to hydrogen and hydrocarbon fuel”.
Using efficient usage of electrons and holes generated by excitation semiconductor materials as the main idea, Gong Jinlong led his research group to begin the design and preparation of the catalyst system.
A New Method of Creating Photocatalytic Water
Based on the innovation of scientific principles, Gong Jinlong’s group achieved a number of progresses in the design and preparation of photocatalytic water hydrogen catalysts.
By promoting the separation and conduction of photo-generated carriers, the suppression of electron-hole recombination is one of the effective means to improve carrier utilization efficiency. Meanwhile, through the nano-porous material design and preparation, shortening the path of photo-generated carriers can effectively inhibit electron-hole recombination.
Zhang Jijie, a doctoral student from Prof. Gong Jinlong’s group, successfully prepared a series of bismuth binary oxide anodic semiconductors by the anion exchange method under solvothermal conditions. At the same time, Li Ang, another doctoral student from the same group, designed a hollow sphere structure constructed through TiO2 - In2O3 thin heterostructures, which was more than twice speed of the traditional titanium dioxide catalyst. Another aspect of this is to increase the rate of photogenerated carriers on the surface of the catalyst. Ph.D. students Chang Xiaoxia and Li Ang improved the efficiency of electron and hole separation, and also increased the surface oxygen reaction rate.
Enhance the Efficiency of Carbon Dioxide Reduction
What's more, researchers studied the surface of the water decomposition reaction path and mechanism. They designed a "double-promoter" system for the two-step reaction of oxygen-generated water to produce oxygen. At the same time, Chang Xiaoxia introduced the system for the carbon dioxide reduction reaction in aqueous solution, and the researchers directed the reaction path of the electrons on the surface of the catalyst in response to the serious problem of the hydrogen production side reaction in the aqueous solution.
Gong Jinlong said that over the years, their research group has made some progress in the artificial light synthesis field under the support of the National Natural Science Foundation and the national key research project. However, due to the complexity of the reaction process, many mechanisms still need further analysis. In the future, they will try to reveal the microscopic mechanisms of artificial photosynthesis from microcosmic and dynamic perspectives, and further guide the efficient synthesis of photocatalysts and realize the efficient conversion of light energy to chemical energy.
China Science Daily: http://news.sciencenet.cn/dz/dznews_photo.aspx?id=26560
