We describe here a one-step method for the synthesis of Au/TiO2 nanosphere materials,which were formed by layered deposition of multiple anatase TiO2 nanosheets.The Au nanoparticles were stabilized by structural defec...We describe here a one-step method for the synthesis of Au/TiO2 nanosphere materials,which were formed by layered deposition of multiple anatase TiO2 nanosheets.The Au nanoparticles were stabilized by structural defects in each TiO2 nanosheet,including crystal steps and edges,thereby fixing the Au-TiO2 perimeter interface.Reactant transfer occurred along the gaps between these TiO2 nanosheet layers and in contact with catalytically active sites at the Au-TiO2 interface.The doped Au induced the formation of oxygen vacancies in the Au-TiO2 interface.Such vacancies are essential for generating active oxygen species（-＊O^-） on the TiO2 surface and Ti^3＋ ions in bulk TiO2.These ions can then form Ti^3＋-O^--Ti^4＋species,which are known to enhance the catalytic activity of formaldehyde（HCHO） oxidation.These studies on structural and oxygen vacancy defects in Au/TiO2 samples provide a theoretical foundation for the catalytic mechanism of HCHO oxidation on oxide-supported Au materials.展开更多
The g-C_3N_4 with different structures was prepared by heat treatment using urea(CN-U) and thiourea(CN-T) as precursors under the same conditions. The microstructure and optical properties of the photocatalyst were an...The g-C_3N_4 with different structures was prepared by heat treatment using urea(CN-U) and thiourea(CN-T) as precursors under the same conditions. The microstructure and optical properties of the photocatalyst were analyzed with advanced tools. The results showed that the CN-U has a porous structure, a high specific surface area and a wide band gap in comparison with CN-T. The in situ FT-IR technique was used to monitor the adsorption and reaction process of visible photocatalytic NO oxidation on g-C_3N_4. The corresponding reaction mechanism was proposed based on the results of reaction intermediate observation and electron paramagnetic resonance(EPR) radical scavenging. It was revealed that(1) the presence of defective sites favored the adsorption of gas molecules and electronically compensated it leading to promoted formation of the final products;(2) the high separation efficiency of photogenerated electron-hole pairs enhanced the production of radicals during the photocatalytic reaction;(3) the hydroxyl radicals(-OH) are not selective for the decomposition of pollutants, which are favorable to the complete oxidation of the reaction intermediates. The above three aspects are the main reasons for the CN-U possessing the efficient visible light photocatalytic activity. The present work could provide new insights and methods for understanding the mechanism of photocatalysis.展开更多
基金supported by the National Natural Science Foundation of China (21107124, 21337003)the Youth Innovation Promotion Association (2011037)Science Promotion Program of Research Center for Eco-Environmental Sciences, Chinese Academic Sciences (No. 121311RCEES-QN-20130046F)
文摘We describe here a one-step method for the synthesis of Au/TiO2 nanosphere materials,which were formed by layered deposition of multiple anatase TiO2 nanosheets.The Au nanoparticles were stabilized by structural defects in each TiO2 nanosheet,including crystal steps and edges,thereby fixing the Au-TiO2 perimeter interface.Reactant transfer occurred along the gaps between these TiO2 nanosheet layers and in contact with catalytically active sites at the Au-TiO2 interface.The doped Au induced the formation of oxygen vacancies in the Au-TiO2 interface.Such vacancies are essential for generating active oxygen species（-＊O^-） on the TiO2 surface and Ti^3＋ ions in bulk TiO2.These ions can then form Ti^3＋-O^--Ti^4＋species,which are known to enhance the catalytic activity of formaldehyde（HCHO） oxidation.These studies on structural and oxygen vacancy defects in Au/TiO2 samples provide a theoretical foundation for the catalytic mechanism of HCHO oxidation on oxide-supported Au materials.
基金supported by the National Key Research and Development Plan (2016YFC02047)the National Natural Science Foundation of China (51478070, 21777011 and 21501016)+1 种基金the Innovative Research Team of Chongqing (CXTDG201602014)the Natural Science Foundation of Chongqing (cstc2017jcyj BX0052, cstc2016jcyj A0481)
文摘The g-C_3N_4 with different structures was prepared by heat treatment using urea(CN-U) and thiourea(CN-T) as precursors under the same conditions. The microstructure and optical properties of the photocatalyst were analyzed with advanced tools. The results showed that the CN-U has a porous structure, a high specific surface area and a wide band gap in comparison with CN-T. The in situ FT-IR technique was used to monitor the adsorption and reaction process of visible photocatalytic NO oxidation on g-C_3N_4. The corresponding reaction mechanism was proposed based on the results of reaction intermediate observation and electron paramagnetic resonance(EPR) radical scavenging. It was revealed that(1) the presence of defective sites favored the adsorption of gas molecules and electronically compensated it leading to promoted formation of the final products;(2) the high separation efficiency of photogenerated electron-hole pairs enhanced the production of radicals during the photocatalytic reaction;(3) the hydroxyl radicals(-OH) are not selective for the decomposition of pollutants, which are favorable to the complete oxidation of the reaction intermediates. The above three aspects are the main reasons for the CN-U possessing the efficient visible light photocatalytic activity. The present work could provide new insights and methods for understanding the mechanism of photocatalysis.
