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Achieving efficient H2O2 production by a visible-light absorbing, highly stable photosensitized TiO2
摘要： In this paper we propose titanium dioxide modified with cobalt(II) 2-ethylhexanoate (Co@TiO2) as photoactive material for the efficient visible light driven production of H2O2. We demonstrate that visible light activity can be achieved thanks to a photoinduced electron transfer from the excited complex towards the TiO2 conduction band that corresponds to a cobalt-to-titanium-charge-transfer transition. H2O2 is synthetized by a combination of oxygen reduction and water oxidation, that is possible thanks to the correct band position of Co@TiO2. A mechanism of H2O2 formation is suggested on the basis of experimental evidences. Reactive oxygen intermediates, together with H2O2 are responsible for the photocatalytic degradation of a nonionic surfactant, of methylene blue and of phenol for wastewater treatments. Finally, and quite interestingly, Co@TiO2 can be also used in a photoelectrochemical setup, where it can be adopted both as photoanode and photocatode, and the switching potential corresponds to the redox potential of the adsorbed complex Co(III)/Co(II) couple.
关键词： photosensitization,charge carrier injection,cobalt(II) 2-ethylhexanoate,surfactant degradation,photocatalysis
更新于2025-09-10 09:29:36
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Photosensitization and Photocatalysis - Perspectives in Organic Synthesis
摘要： Photochemical sensitization and photocatalysis have very similar definitions and are closely related. Each of the two terms are preferentially used in different scientific communities. Three types of processes are discussed: (1) sensitization involving energy transfer, (2) photocatalysis in which hydrogen abstraction plays a key role and (3) photoredox catalysis in which electron transfer is involved. The processes are discussed in connection with [2+2] photocycloadditions and C-H activation, which are of particular interest for organic synthesis.
关键词： [2+2] Photocycloaddition,Photosensitization,Energy transfer,Hydrogen atom transfer,Electron transfer,C-H activation,Photocatalysis
更新于2025-09-09 09:28:46
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Contribution à l’étude de la désinfection de l’eau par photosensibilisation avec des extraits de plantes
摘要： Some plants used in the traditional pharmacopoeia to treat microbial and parasitic infections are able to generate singlet oxygen. This is used to disinfect the water. The study of the disinfection of water by photosensitization with the flavonoid extracts of Aframomum alboviolaceum shows a complete inhibition of fecal coliforms present in the water after one hour of sunshine for the two isolated products by column chromatography of the roots of this plant. Regarding the water samples treated with these two products and kept in the dark, no inhibition was noted from the beginning to the end of the experiments. This suggests that these products are photosensitizers and that in the presence of the sun they undergo photoexcitation which would lead to the formation of singlet oxygen. The latter, once generated, destroys the fecal coliforms present in water.
关键词： Photosensitization,Flavonoids,Singlet oxygen,Aframomum alboviolaceum,Sunstroke time
更新于2025-09-04 15:30:14