Hydrogen, the cleanest and most promising energy vector, can be produced by solar into chemical energy conversion, either by the photocatalytic direct splitting of water into Hand O, or, more efficiently,in the presen...Hydrogen, the cleanest and most promising energy vector, can be produced by solar into chemical energy conversion, either by the photocatalytic direct splitting of water into Hand O, or, more efficiently,in the presence of sacrificial reagents, e.g., in the so-called photoreforming of organics. Efficient photocatalytic materials should not only be able to exploit solar radiation to produce electron–hole pairs, but also ensure enough charge separation to allow electron transfer reactions, leading to solar energy driven thermodynamically up-hill processes. Recent achievements of our research group in the development and testing of innovative TiO-based photocatalytic materials are presented here, together with an overview on the mechanistic aspects of water photosplitting and photoreforming of organics. Photocatalytic materials were either（i） obtained by surface modification of commercial photocatalysts, or produced（ii） in powder form by different techniques, including traditional sol gel synthesis, aiming at engineering their electronic structure, and flame spray pyrolysis starting from organic solutions of the precursors, or（iii） in integrated form, to produce photoelectrodes within devices, by radio frequency magnetron sputtering or by electrochemical growth of nanotube architectures, or photocatalytic membranes, by supersonic cluster beam deposition.展开更多
Perovskite-type La1-xCexMnO3 （x= 0-10%） catalysts were prepared by flame spray pyrolysis and their activities during the catalytic oxidation of benzene were examined over the temperature range of 100-450 ℃. The str...Perovskite-type La1-xCexMnO3 （x= 0-10%） catalysts were prepared by flame spray pyrolysis and their activities during the catalytic oxidation of benzene were examined over the temperature range of 100-450 ℃. The structural properties and reducibility of these materials were also characterized by X-ray diffraction （XRD）, N2 adsorption/desorption, H2 temperature-programmed reduction （H2-TPR） and X-ray photoelectron spectroscopy （XPS）. The incorporation of Ce was found to improve the benzene oxidation activity, and the perovskite in which x was 0.1 exhibited the highest activity. Phase composition and surface elemental analyses indicated that non-stoichiometric compounds were present. The incorporation of Ce had a negligible effect on the specific surface area of the perovskites and hence this factor has little impact on the catalytic activity. Introduction of Ce^4＋ resulted in modification of the chemical states of both B-site ions and oxygen species and facilitated the reducibility of the perovskite. The surface Mn^4＋/Mn^3＋ ratio was increased as a result of Ce^4＋ substitution, while a decrease in the surface-adsorbed O/lattice O （Oads/Olatt） ratio was observed. The relationship between the surface elemental ratios and catalytic activity was established to allow a better understanding of the process by which benzene is oxidized over perovskites.展开更多
基金supported by Fondazione Cariplo through Grants 2009-2477 and 2013-0615
文摘Hydrogen, the cleanest and most promising energy vector, can be produced by solar into chemical energy conversion, either by the photocatalytic direct splitting of water into Hand O, or, more efficiently,in the presence of sacrificial reagents, e.g., in the so-called photoreforming of organics. Efficient photocatalytic materials should not only be able to exploit solar radiation to produce electron–hole pairs, but also ensure enough charge separation to allow electron transfer reactions, leading to solar energy driven thermodynamically up-hill processes. Recent achievements of our research group in the development and testing of innovative TiO-based photocatalytic materials are presented here, together with an overview on the mechanistic aspects of water photosplitting and photoreforming of organics. Photocatalytic materials were either（i） obtained by surface modification of commercial photocatalysts, or produced（ii） in powder form by different techniques, including traditional sol gel synthesis, aiming at engineering their electronic structure, and flame spray pyrolysis starting from organic solutions of the precursors, or（iii） in integrated form, to produce photoelectrodes within devices, by radio frequency magnetron sputtering or by electrochemical growth of nanotube architectures, or photocatalytic membranes, by supersonic cluster beam deposition.
基金the financial support of the National High Technology Research and Development Program of China(Grant Nos.2012AA062702 and 2010AA064903)the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No.XDB05050300)+2 种基金the National Natural Science Foundation of China(No.21306199)the Instrument Developing Project of the Chinese Academy of Sciences(Grant No.YZ200722)the 12th Five-years National Key Technology R&D Program(Grant Nos. 2012BAJ02B03 and 2012BAJ02B07)
文摘Perovskite-type La1-xCexMnO3 （x= 0-10%） catalysts were prepared by flame spray pyrolysis and their activities during the catalytic oxidation of benzene were examined over the temperature range of 100-450 ℃. The structural properties and reducibility of these materials were also characterized by X-ray diffraction （XRD）, N2 adsorption/desorption, H2 temperature-programmed reduction （H2-TPR） and X-ray photoelectron spectroscopy （XPS）. The incorporation of Ce was found to improve the benzene oxidation activity, and the perovskite in which x was 0.1 exhibited the highest activity. Phase composition and surface elemental analyses indicated that non-stoichiometric compounds were present. The incorporation of Ce had a negligible effect on the specific surface area of the perovskites and hence this factor has little impact on the catalytic activity. Introduction of Ce^4＋ resulted in modification of the chemical states of both B-site ions and oxygen species and facilitated the reducibility of the perovskite. The surface Mn^4＋/Mn^3＋ ratio was increased as a result of Ce^4＋ substitution, while a decrease in the surface-adsorbed O/lattice O （Oads/Olatt） ratio was observed. The relationship between the surface elemental ratios and catalytic activity was established to allow a better understanding of the process by which benzene is oxidized over perovskites.
